Interview Questions.

Question 1. What Is Pi?

Answer :

PI became previously known as PROFIBUS International. It is the umbrella enterprise responsible for the PROFIBUS protocol and its merchandising and guide across the world thru a network of Regional PI Associations. When PROFINET, PI’s Industrial Ethernet answer, turned into released, PROFIBUS International became re-named ‘PI’ (PROFIBUS and PROFINET International).

Question 2. How Do I Terminate The Shielding Of The Cable?

Answer :

It is suggested to attach the guard on both ends low inductively to ‘ground’ to be able to reap best electromagnetic compatibility. In the case of separate potentials (e.G. In a refinery) the defend must be related simplest on one quit of the cable to ‘ground’. Preferably, the connection between defend and shielding ground have to be made via the metal cases and the screw top of a D-sub connector. If this is not viable the relationship may be made via pin 1 of the D-sub connector. It need to be observed that this isn't always the most suitable answer. In this kind of case it is higher to naked the cable guard at the suitable factor and to floor it with a cable as quick as feasible to the metallic shape of the cabinet. This may be carried out with a ground bus bar in front of the bus connector.

Programmable Logic Controller (PLC) Interview Questions
Question three. What Is Profibus-dp?

Answer :

This is the performance optimized model of PROFIBUS, specially committed to time-important verbal exchange between automation structures and dispensed peripherals. It is appropriate as a substitute for the highly-priced parallel wiring of 24 V and 4(zero) to twenty mA size signals. PROFIBUS-DP is covered into the European Fieldbus Standard EN 50170.

Question 4. Indent Numbers: What Are They, Where Do I Get Them?

Answer :

Every DP/PA tool type has to have an character indent Number. This wide variety is vital so that a DP-grasp is capable of perceive the styles of the connected DP/PA gadgets with out a vast protocol overhead. The grasp compares the indent Number of each linked device with the indent Number in the configuration database. User information switch within the operation segment is handiest feasible whilst the proper DP Slave is attached to the perfect cope with. This guarantees very high protection towards parameterization faults. The companies have to apply to the PROFIBUS Support Center for an person indent Number for each DP/PA device type.

Question 5. What Is Profibus Pa?

Answer :

PROFIBUS-PA is a ‘profile’ of PROFIBUS designed particularly to be used in system automation for connecting control systems with subject contraptions. PROFIBUS-PA is based totally on PROFIBUS-DP and, the use of a linking device known as a section coupler, lets in transparent conversation among preferred reason automation and system automation networks, making PROFIBUS best for hybrid packages where manufacturing unit and method devices intermingle. The PROFIBUS PA profile defines the behavior of the field gadgets and ensures full interoperability and interchangeability among one-of-a-kind producers. PROFIBUS PA operates both with Intrinsically Safe transmission generation (acc. To IEC 61158-2) or preferred transmission era (acc. To RS485). In summary, PROFIBUS PA fulfils the unique necessities of all sectors of the technique industry as follows:

Transparent communique between technique automation networks and wellknown cause automation networks is possible.
PROFIBUS PA lets in powering of the sector devices and information transmission over the identical  wires.
PROFIBUS PA may be utilized in doubtlessly explosive atmospheres the usage of Intrinsically Safe transmission era consistent with IEC 61158-2.
Fix Protocol Interview Questions
Question 6. What Are The Basic Configurations In Profibus Communication Protocol For Interfacing Plc, Hmi, Field Instruments?

Answer :

Profibus or system field bus is virtual commercial verbal exchange device that use physical mediums consisting of optical fiber or copper cable for data change. Profibus is assessed into the following categories.

Profibus FMS
Profibus DP
Profibus PA
Profi-Drive
Profi-Safe
1. Profibus FMS (discipline messaging device) is an out of date now. Honestly i don’t know an awful lot approximately it.

2. Profibus DP (Decentralized Peripheral) is used for interfacing PLC, Remote IO Systems, Variable Frequency Drives, and HMI’s, Encoders, Sensors, Actuators and other comparable devices. It uses RS 485 technology. As of now DP V-2 is the trendy version.

Three. Profibus PA (Process Automation) is used for interfacing discipline measuring gadgets including float transmitters, strain transmitters and many others. It makes use of Manchester Coding technology.

Four. Profi-Drive is used for motion control applications (Controlling of Servo automobiles in position control mode).

5. Profi-Safe is used for Fail Safe applications.

Question 7. Hamming Distance (hd): What Does It Mean?

Answer :

The hamming distance is a measure for how secure a protocol is against misinterpretation of a packet.. HD=4 tells us that at least 4 bits have to be wrong, but still in shape the checksum calculations, in order for it to be unsuitable as a legitimate packet.

Question 8. Why Are Terminators Important?

Answer :

Termination of the bus prevents sign reflections at the PROFIBUS cable. Wrong or missing termination effects in transmission errors when the worst case result is that the communication hyperlink is misplaced. In addition, the PROFIBUS termination provides a defined ‘idle’ stage for the cable.

Question 9. What Is A Profile? Which Are Available?

Answer :

Profiles are definitions of non-mandatory services and parameters for unique areas of applications. It facilitates to decrease the implementation efforts to implement PROFIBUS functionality in suitable discipline devices.

Question 10. What Are The Main Advantages Of Profibus Over Other Fieldbus Types?

Answer :

This is a subjective difficulty but – provided that the technical solution is excellent for the project – it boils right down to fee/advantage comparisons. PROFIBUS offers users with the nice possible, destiny proof bus system that may deal with the huge desires of manufacturing unit and manner automation. Market popularity and sheer momentum manner that PROFIBUS is a de-facto fieldbus wellknown during the sector.

Here are a number of the data:

PROFIBUS has the largest portfolio of merchandise inside the fieldbus global. In 2008 it reached 2400 products and services.
It has the most important set up base. At the cease of 2008 the total had handed 28 million and by way of 2012 it's miles anticipated to attain 50 million.
It is supported by using the most important user agency in this enterprise. PI had over 1400 individuals at the quit of 2008.
There are 24 Regional PI Associations global, making sure neighborhood help in all industrialized regions.
There are close to four hundred carriers of PROFIBUS products and services, subsequently there may be lots of preference for customers.
It’s supported with the aid of manufacturers of each master and slave devices supplying a surely open approach and sensible supplier independence.
Choice drives opposition among carriers, main to price, supply and performance blessings for stop users..
PROFIBUS generation can be used for numerous levels inside the records glide in a business enterprise.
Knowledge of one general may be applied on numerous stages.
There’s extensive utility capability throughout manufacturing facility, method and constructing automation.
It’s a stable protocol with many chip options available nowadays.
It’s suitable for operation in intrinsically secure areas in procedure manage.
It is the simplest fieldbus that may be used in hybrid applications – in which process and discrete automation segments co-exist in a plant.
Platform independence means PC, PLC and DCS based totally controllers are available.
244 byte telegram manner that big packets of information may be despatched without segmentation.
> 100km distance is practicable the usage of fiber optics.
Question eleven. Why Are Class 1 And Class 2 Masters Different?

Answer :

A Class 1 master can speak actively simplest with its configured slaves and is capable of communicate in a passive way with a Class 2 master. The class 2 master is the ‘supervisory’ tool. It can communicate with Class 1 masters, their slaves and its very own slaves for configuration, diagnostic and records/parameter alternate functions.

Question 12. What Is A Fail Safe Mode? What Does A Fail Safe Mode Mean?

Answer :

This mode defines the repute of alerts in IO modules if a bus or device failure occurs. It is common that all output signals are going to the 0 voltage degree in a failsafe situation. The fame is essential in practical safety programs where a profile which includes PROFIsafe is used.

Programmable Logic Controller (PLC) Interview Questions
Question thirteen. Why No Signal Ground/reference Wire Is Used In Profibus Cables?

Answer :

To ensure clean handling a signal ‘ground’ cord is not utilized by PROFIBUS. However, it's far encouraged to isolate the interface circuit from the neighborhood ground (e.G. The use of Optocouplers) to reduce viable commonplace mode voltages among transceivers.

Question 14. Is Profibus An Open Or Proprietary System?

Answer :

PROFIBUS is completely open. It became in the beginning standardized in Germany in 1989 as DIN 19245 and in July 1996 as EN 50 one hundred seventy. The EN 50 170 specification is available thru any of the countrywide requirements our bodies of CENELEC / IEC and the PROFIBUS Specification may be provided by means of any of the Regional PROFIBUS Associations. It’s now globally standardized underneath IEC 61158.

Question 15. Is It Possible To Calculate A Cost Per Device For A Profibus System?

Answer :

Not normally however PROFIBUS connectivity must not upload substantially to traditional area device charges as most devices nowadays are digitally based totally besides. It’s extra instructive to have a look at wider issues. Having a single cable to attach gadgets manner large financial savings in design, engineering and installation fees. Furthermore, the provision of information across the plant means even greater savings are possible over the life of a tool thru higher operations and improved asset control. Better statistics flows cause better plant control too. Overall, any greater fee consistent with device is insignificant compared with the existence cycle savings of a fieldbus community.

Question sixteen. What Is A Gsd File?

Answer :

A GSD record is used to discover the primary operational traits of a PROFIBUS device, to resource interoperability and interchangeability. It makes it possible to have manufacturer-independent configuration equipment. Typically, a GSD document consists of seller information, baudrates, timing facts, the options or capabilities supported and the available I/O indicators. A GSD file have to be to be had for each PROFIBUS slave.

Question 17. What Are The Roots Of Profibus?

Answer :

The base of the specification of the PROFIBUS popular become a research task that came about among 1987-1990, supported with the aid of the following groups: ABB, Phoenix Contact, AEG, Rheinmetall, Bosch, RMP, Honeywell, Sauter-Cumulus, Kloeckner-Moeller, Schleicher, Landis & Gyr, and Siemens.

Five German research institutes additionally supported the mission: FZI Karlsruhe, LRT, IITB, WZL, and LPR
There became also minor sponsorship from the German authorities.
The result of the venture became the primary draft of DIN 19245, the PROFIBUS standard.
Question 18. What If My Profibus System Should Fail Or A Chip Fails In A Device?

Answer :

PROFIBUS has been designed to permit configurations in which redundant cabling is feasible to take account of twine breaks. Also, node disasters may be configured to be left out, or to cause a ‘prevent’ within the master. In this example unaffected nodes can hold operation. When a failure is identified the master immediately resends the telegram and it’s feasible to configure the range of times this is tried. Information relating to the failure is commonly to be had on a node, a module inside a node and on a channel specific foundation. Certification trying out of gadgets via a certified take a look at laboratory ensures that capability disasters conform to what's expected of them. Media redundancy may be carried out through dual master systems.

Fix Protocol Interview Questions
Question 19. Can New Devices Be Added To A Profibus System Without Upgrading The System?

Answer :

PROFIBUS guarantees backwards compatibility. So, if new capabilities are supplied in a device it's going to nevertheless be possible to use this device at the same cord with older gadgets, allowing development of the device with out forcing customers to upgrade until they especially wish to beautify their functionality.

Question 20. What Hardware And Software Is Needed To Set Up A Profibus System?

Answer :

In addition to a PLC and the gadgets to be controlled:

A cable – Shielded Twisted Pair with terminating resistors or Fibre Optic with Optical Link Modules.
A GSD report for each tool. (A easy ASCII text report containing tool facts like identity data, what transmission speeds are supported, statistics format, time required to respond and so on.).
A software program configuration device. This configures the lively stations and tells them what devices are gift on the bus and how much facts it desires to exchange with them and many others. Is required.
Question 21. What Connectors, Pin Out And Mandatory Signals Are Used?

Answer :

The PROFIBUS Standard does now not specify an alternative to the 9 pin D-SUB connectors, however it is regularly necessary to have alternatives available.

The test specification for DP Slaves defines:

Alternative connectors can be used. No unique connector is described. But if the device with those opportunity connectors should be certified, it should have all of the obligatory indicators of the PROFIBUS D-SUB connector available.
Furthermore, you ought to think about for high velocity utilization, that some additional additives have to be utilized in mixture with the D-SUB connector, or another one.
These components (R, L, C) are targeted into the Implementation Guideline for PROFIBUS-DP, and are defined in detail which includes sample circuit diagrams in the new PROFIBUS-DP e book (The Rapid Way to PROFIBUS-DP). This book may be ordered from your neighborhood PROFIBUS enterprise.
Question 22. Are There Any Particular Applications Or Sectors Of Industry That Particularly Benefit From Profibus?

Answer :

PROFIBUS has already found many packages in factory, system and building automation, for example from automobile manufacture at General Motors across Europe, to Breweries like Bit burger and Guinness to building management just like the Russian Kremlin constructing. PROFIBUS is also being utilized in applications that had been never envisaged from its conception, because it has been built in a manner that permits for lots new device types to be delivered.

However, the 2 key areas of enterprise that could maximum advantage from its adoption are:

Factory Automation, wherein sign wiring fees are cut notably and plenty of gadgets may be mounted at once at the bus, therefore putting off the want for many input and output indicators.
Process Automation, wherein cabling prices are substantially decreased; gadgets may be located at once within the dangerous regions; many analogue I/O cards may be eliminated through moving all statistics on one twisted pair cable. This additionally reduces the need for I/S barriers.
Question 23. Profibus Cable Specifications: What Should I Use?

Answer :

The PROFIBUS preferred defines  variations of the bus cable. However it's far recommended to use cable Type A in all new installations.

Type A is usually recommended for excessive transmission speeds and permits a doubling of the community distance in assessment to Type B.

Type A Technical specification:

Impedance: 35 up to 165 Ohm at frequencies from three to twenty MHz.
Cable potential: < 30 pF per meter.
Core diameter: > 0,34 mm², corresponds to AWG 22.
Cable kind: twisted pair cable. 1×2 or 2×2 or 1×4 lines.
Resistance: < 110 Ohm per km.
Signal attenuation: max. 9 dB over total length of line section.
Shielding: CU shielding braid or shielding braid and shielding foil.
Max. Bus length: 200 m at 1500 kbit/s, up to 1,2 km at 93,75 kbit/s. Extendable by repeaters.
Question 24. What Is Profibus?

Answer :

Profibus is a building automation communications standard which defines application layer data and physical connections.

PROFIBUS (Process Fieldbus) Is An industrial control network used for factory automation, process control, motion control and safety networks. Using master/slave architecture, specialized “Profiles” are used to support each of these areas.

Several messaging could be added over PROFIBUS:

Profibus DP
Profibus S7
Profibus S5
Profibus MPI
Question 25. What Is Profibus Dp?

Answer :

PROFIBUS DP (Decentralized Peripherals) is used to operate sensors, actuators and input/ output deported via a centralized controller. On a PROFIBUS DP network, 126 equipments could be connected. Each equipment could support up to 244 input/outputs. PROFIBUS DP is a fast protocol. The communication can be established up to 12M Bauds. PROFIBUS DP is deterministic due to its timing configuration (cyclic communication). Acyclic requests are also possible.

Question 26. What Is Profibus Dpv1?

Answer :

Profibus DPV1 is used to read or write some record memory bloc (via slot, index). Several profiles normalized these records (area memory). DPV1 is based on two modes: Class 1 and Class2. DPV1 is based on top of DPV0.

Question 27. What Are Dpv0/dpv1 Class1 And Class2?

Answer :

With Profibus DPV0 and DPV1, two communications types are available:

Class1 is defined when the device belongs to a master (connection established/ cyclic IO data exchanged).
Class2 is used to communicate with a device without establishing an IO connection. In case of DPV1, since there is no established connection, a specific connection (initiate request) is established.
Question 28. What Is Fdt/dtm?

Answer :

FDT/DTM standardizes the communication and configuration interface between all field devices and host systems. Any devices can be configured, operated, and maintained through this standardized user interface regardless of supplier, type or communication protocol. The FDT/DTM describes interface that standardized data exchange between devices and control system or engineering or asset management tools.

Elements in FDT/DTM architecture are:

FDT Frame: This element is a container that allows embedding DTMs. FDT Frame offer services like user management, project management and services that allow communication between DTMs.
DTMs: DTMs are classified into two categories:
Comm. DTMs: Represents communication components like PC communication cards, couplers, gateways, remote I/Os, and linking devices.
Device DTMs which connect to the field device configuration components (e.G: Profibus: DP, DPV1, PA device). DTM is provided by the device manufacturer and represents the whole logic and parameters of a device.
Question 29. What Is Profiles?

Answer :

Several profiles are available for Profibus DP (profisafe, profidrive). This profile defines the memory mapping of each record memory. A profile defines a common interface that allows changing a device compliant to a profile by a device from a competitor supporting the same profile, with no change required on the PLC program.

Question 30. What Is Freeze And Sync?

Answer :

The freeze command is used to freeze the slave inputs; the sync command is used to synchronize the slave outputs. The group must be defined during the configuration. This feature uses a broadcast telegram (global control). The slave diag command can be used to know if the freeze or sync modes are enabled or not.

Question 31. What Is Set Slave Address Command?

Answer :

The set slave address command provides a mechanism to set a Profibus station address to a slave. This feature can be used to replace a slave by another without manual configuration. This address can be stored in permanent mode or volatile mode by the slave.

Question 32. What Is S7/s5 Mpi?

Answer :

S7 is a messaging allowing communicating with all SIMATIC S7 PLC. This messaging is offered on TCP/IP and PROFIBUS. The molex product supports this messaging on several products (Ethernet, Profibus). Through Profibus S7, several distinct memory area are accessible (write or read) MEMENTO, DB, TIMER, COUNTER,… Different kinds of connections are possible: CPU socket via MPI and S7 COMMUNICATION COUPLER via Profibus S7. The range of SIEMENS PLC supporting this protocol is wide. This messaging is based on the Client/Serveur model. A Server can accept several connections. The applicom Products support all S7 equipments (S7-200, S7-300, S7-400 and S7-1200).

The messaging S5 is similar to S7 messaging but dedicated to SIMATIC S5 PLC.

Question 33. What Is The Maximum Number Of Nodes That The Network Can Support?

Answer :

PROFIBUS allows up to 32 nodes per segment and up to 126 nodes for one network.

Question 34. What Is The Bus Topology?

Answer :

The base technology is a line which allows connection and removal of nodes at any time without breakdown.

PROFIBUS allows ring and star topology as well with fiber optics.

Question 35. What Types Of Transmission Media Are Used And Supported?

Answer :

Copper cable (shielded twisted pair- known as IBM type 1 cable)
Solid and stranded cable
Specialized materials for plastic surrounding
Fiber optic
In glass
In plastic
Infrared
Question 36. How Many Bits Are Allocated At A Node For Input And Output Data?

Answer :

PROFIBUS allows between 0 and 244 byte, determined by the device requirements for input and output each.

Question 37. How Is The Bus Powered?

Answer :

There is no specialized bus power supply. The terminal resistors with pull-up and pulldown are located at the end of the line and powered be the devices on that place. One combination is enough to run the system.

Question 38. If The Bus Provides Power To Field Devices What Current Level Is Available?

Answer :

PROFIBUS PA does supply power for intrinsic safe devices connected with twisted pair. This is done according to IEC 1158-2 specification (maximum current is 120 mA per coupler for intrinsic safe operation and >300mA for non intrinsic safe operation).

Question 39. How Are Node Addresses Set?

Answer :

Two techniques are supported:

DIP switches or comparable strategies.
Setting of the node address thru the bus connection
Any desire is viable.
Question forty. Does The Bus Provide Duplicate Address Detection?

Answer :

Configuration assessments for reproduction addresses.
Masters will search for duplicate addresses before entering the token ring and when sudden frames are acquired.
Slave need to be installation with their Ident-variety and with their configuration. In case of a mismatch, this could be reported to the grasp’s utility.
Question forty one. Does The Bus Provide An Address Attendance Check After The First Scan?

Answer :

through a so called stay listing.
Scanning of configured slaves is accomplished cyclic.
Scanning for brand spanking new masters is achieved all time.
Question 42. Does The Bus Provide A Node Configuration Check After The First Scan?

Answer :

Yes, with the function config_check after strength up. In addition, the Ident quantity is likewise checked.

Question forty three. Does The Bus Provide Error Detection And Correction Algorithms?

Answer :

PROFIBUS has a diffusion of blunders detection abilties:

Checkbits in each byte
Checksum for each message
Start delimiters for efficient body detection
Addressing facts (supply and destination)
Inactivity detection to find out the start
Transmitter check at the grasp gadgets
Monitoring the token passing methods
The error correction is achieved by way of retries.
PROFIBUS includes message duplication competencies
Question 44. Can A Node Provide Parameter Programming. Examples Logic Inversion And Similar Boolean Operations. Explain Any Extended Detection?

Answer :

There are several methods for parameter setup:

PROFIBUS lets in the person set of parameters (a most of 237 Bytes) at some point of the startup.
Acyclic exchange of parameters at runtime.
Parameter load from a PC with the aid of a 2nd grasp.
Question forty five. What I/o Granularity Does The Bus Support?

Answer :

The minimum is one byte:

The granularity is determined by the tool.
Integer, unsigned, floating factor, string and structures of the bottom kinds are viable.
A node might also have IO-modules with the granularity of one bit.
There are various links to be had connecting subordinated bit-degree busses (i.E. AS-I)
Question forty six. What Minimum Address Space Allocation Does The Bus Provide?

Answer :

This is decided with the aid of the device, the minimum would be one byte.

Question forty seven. What Is The Protocol Efficiency Of This Bus?

Answer :

The protocol performance may be up to 70%.
The configurations mentioned in the overall performance metrics phase have a efficiency of
forty%. This parent is configuration dependent.
Question 48. Does The Bus Support Multiple Protocols?

Answer :

PROFIBUS FMS
DP
DP extensions
May use the identical hyperlink and can be implemented in one node.

Question forty nine. What Diagnostic Systems Are In Place To Verify Proper Drop And Node Connections?

Answer :

Several diagnostic gear are to be had which allow measuring the bus and connectors for proper installation.
A easy electric powered meter will do it for most cases (a section unpowered has a resistance of 110 to a hundred thirty Ohms for midrange cable duration).
Question 50. Can The Bus Be Enabled In Segments To Minimize Troubleshooting Requirements?

Answer :

Segmenting can be executed via use of repeaters or optical link modules.
Step-with the aid of-Step begin up can be completed through the connectors through the usage of the incorporated termination.
Question 51. What High Level Tools Are Available For Network Diagnostics?

Answer :

Every PROFIBUS Master allows distinctive diagnostic feature inside the utility.

Diagnostic statistics of every man or woman slave(Type of Slave, availability, various status records)
Diagnostic evaluation of all slaves
Master Diagnostic records
Statistic counter
Service engineers can use a bus display which lets in tracing the bus.

Monitoring all data
Hardware filtering mechanism
Time stamps
Trigger situations
Special activities
Question 52. Can A Network Configuration Be Restored Remotely?

Answer :

Network down load protocol is defined within the standard.

Some System have proprietary protocols to save you inconsistencies (network configuration and PLC configuration are NOT unbiased).

Question fifty three. Does The Bus Provide Tools For Throughput Monitoring Enabling The User To Check The Validity Of Various Node Configurations?

Answer :

Various configuration equipment offer such functionality as well the bus screen.
Most customers look on response time as opposed to cycle time which encompass the PLC test.
Question 54. Does The Bus Support Any Kind Of Hot Swap Capability?

Answer :

PROFIBUS permits changing of devices with out interrupting the bus traffic to linked nodes.
Slave devices want not be configured in case of a switching in the masters position.
Question fifty five. How Long Would It Take To Update A Network With sixteen Nodes Of 256 Digital I/o (4096 Total Points)?

Answer :

1.09ms through 12MBaud
6,71ms by using 1.5MBaud
Question fifty six. What Is The Best And Worst Case Repeat Ability Of This Configuration?

Answer :

The nice case that is 99% the normal case is that the timing is absolute stable (5% jitter is possible due to control features)
In case of a failure (stations are dropping out) the timing can trade
1 transmission failure will be corrected inside 500/100μs (1,five/12Mbaud)
1 station failure will add a jitter of seven hundred/300μs
A worst case situation of 33ms by way of 1.5MBaud or 6.6ms by means of 12MBaud for one cycle will occur while all stations fail (in this example the response time is meaningless).
After the failure detection the timing is back to the ordinary cycle time.
Question 57. How Long Would It Require Updating A Network With 256 Analog I/o Points? (16 Bit Words)?

Answer :

It is exactly the equal time as less than 1. PROFIBUS makes no distinction inside the format. 256 words is identical to 4096 I/O factors. I’m assuming that we have 256 words in every direction, 256 input words and 256 output words. A difference can occur in your grasp station. The PLC or PC might make a distinction in calculating I/O or analog values. PROFIBUS makes no difference.

Question 58. How Well Will This Implementation Scale With Respect To Improvements In Raw Bit Rate Transmission?

Answer :

There is transmission speed detection in nearly every slave tool as well as repeaters. This will enable the consumer to trade the Baud charge by way of truely changing it on the grasp’s website.
PROFIBUS has more desirable transmission pace 2 times. There is no trouble with the diverse devices due to the fact all functions can also run at a simple configuration.
Question 59. Can Portions Of The Network Be Scanned More Frequently Than The Entire System?

Answer :

A alternate of the cyclic listing is feasible, but due to the fast cycle it isn't vital in common programs. There is a opportunity to send low frequent cyclic messages as acyclic messages.

Question 60. Can Larger Consecutive Blocks Of Data Be Moved Using Block Transfer?

Answer :

Yes, with all protocols.

Question 61. What Attributes Of You System Qualify As A Best In Class?

Answer :

Deterministic, velocity, ease to use, recognition, support, diagnostic, multi protocols.
PROFIBUS offers a notable flexibility. This enables the software engineer to make his layout without counting bits and bytes. One byte greater is less than 1μs! Error recuperation might be completed quickly with out consumer interplay.
It easy to combine PROFIBUS in field gadgets.
PROFIBUS is a very robust protocol with wonderful blunders handling skills.
PROFIBUS-DP lets in transmission of IO-Data with short response time this include transportation from IO to the bus and from the bus to the application.
PROFIBUS-DP may be configured with out precise communique understanding. The tool version is precisely what matters in faraway IO.
PROFIBUS DP is what the person needs in general.
Question 62. What Happens If The Profibus Cable Has A Short Circuit?

Answer :

A brief-circuit at the PROFIBUS cable can disturb a information communication within the unique segment. The devices in that location will NOT get broken! The quick-circuit can without difficulty be detected with an oscilloscope and even the space to the problem may be measured. If the give up-consumer desires to maintain the installation strolling at some stage in a brief circuit.

He can choose the following answers:

Install a redundant device.
Divide the set up in multiple parallel segments coupled by using repeaters, OLMs or Profibus and ComBricks.
Install the cable in separate cable trays.
Question 63. Why Are Termination Problems The Most Common Fault?

Answer :

A lot of people are aware that termination needs to be powered and activated at both ends of the cable. What they do not recognise, is that it must be activated once more whilst you are using repeaters, OLMs or Profibus. Every segment must be terminated! This frequently slips in while human beings are the usage of plenty of fibre optic and there's only a brief duration of copper cable inside the cabinets. Even this short cable must be terminated at each ends.

Question 64. Will The Profibus Plugs With Diagnostic Leds Have Influence On The Busload?

Answer :

The input resistance of the diagnostic plugs is approx. 1,five..2,0 MOhm (analog comparator enter). This is a hundred instances higher because the RS 485 receiver input impedance. In theory this need to no longer motive any troubles which have now not been detected up to now.

Question sixty five. How Many Profibus Dp Repeaters Can Be Installed In Series?

Answer :

There are lots of memories accessible concerning this problem. The actual answer lies in the digital components of the repeater. These determine the actual “most wide variety. The digitalization from and to the opto-couplers inside the repeater will make bits smaller or wider. If you put too many repeaters in series, the bits differentiate too much and messages are not identified anymore. There are also repeaters to be had with no restriction in serial placement.

Check the manual of the repeater! It should state the most amount. For instance: the Siemens repeater is nine, the Profibus is limitless.

The 2nd step is converting the bus parameters. All repeaters have a postpone time. If you placed a huge quantity of repeaters in collection you would possibly need to trade the Tslot bus parameter to a better cost.

Question sixty six. Why Is Termination Important?

Answer :

Termination prevents reflections that may disturb the facts communique. The better the baudrate and the longer the cable, the extra important termination will become. Termination must be activated/positioned at each ends of each bus phase. With PROFIBUS DP the termination is powered to offer an idle stage when no person is sending records. With PROFIBUS PA the termination is a combination of a resistor and a capacitor.

Question 67. Should There Be Distance Between Profibus And Power Cables?

Answer :

YES, even PROFIBUS can get disturbed with the aid of interference resulting from parallel excessive voltage electricity strains. Always try and have at least 10 cm air area between the cables (relies upon on the extent of the voltage). Most users blend all cables in one cable tray and that often ends in unreliable behaviour. Cables that pass each different will now not cause issues. Creating distance isn't always the best requirement. Correct protecting is also a need to.

Question sixty eight. Can You Give Some Basic Tips For Installing A Profibus Dp Network?

Answer :

Always use PROFIBUS cable and connectors.
Do now not exceed 32 devices in line with section (which includes repeaters, OLMs and couplers).
Make positive the phase duration is in comparison with the baudrate.
Make positive every section has powered termination on each ends.
Avoid spur lines.
Avoid swapping the wires (A=green, B=red).
Mark how lengthy the cables truely are and update the drawings.
Question sixty nine. Can I Install Profibus Dp Cable In A Pa Network?

Answer :

Lots of users have the impact this can never motive a hassle due to the excessive velocity signal traits of DP cable (although the impedance isn't always correct), however there are other elements that could make it very volatile

There might be an excessive amount of voltage loss at the cease of the cable because of the better loop resistance of standard DP cable (110 Ohm/km). PA cable has a loop resistance of 44 Ohm/km. When it is an Ex coupler with simplest 12.XV output, there is a change the final devices “wander off” all of the time”.
The DP cable gets over-powered because of its “skinny” 0.64 mm diameter wires. PA cable wires have a diameter between 0.8 to at least one.5 mm.
PA Coupling components cannot handle the “thin” wires of the DP cable.
When it is an Ex set up, the DP cable might be now not blue and no longer suitable for the FISCO Ex specifications.
Our advice is to use most effective cable that complies with the PA specifications.

Question 70. What Is The Minimum Distance Between 2 Devices On Profibus Dp?

Answer :

When the transmission speed is 1,5 Mbps or higher, it is incredibly advocated to have as a minimum 1 m of cable between 2 devices. De input capacitance of each devices may be compensated by using the cable so that you can hold the not unusual impedance. When the devices would be very close collectively, there is a big danger the enter capacitance reasons reflections inside the facts communique (small quick circuits). The effect is a great deal much less at transmission speeds lower than 1, five Mbps.

Question 71. Does Profibus Dp Cable Always Have A Violet Color?

Answer :

NO, because of positive application, protection and isolation classes, PROFIBUS DP cable will have any other colour. Example: ground cable and shipboard cable are black, strong cable is inexperienced. The popular cable is continually violet.

Question 72. Can 2 Profibus Cables Be Installed Inside The Same Metal Conduit?

Answer :

Yes, more than one (parallel) Profibus cables can be established in a steel conduit. It gives good behaviour whilst EMC is involved.

Question 73. What Is The Most Commonly Used Transmission Speed?

Answer :

1.Five Mbps is the most generally used transmission speed. This is the default pace when you create a brand new challenge. Most customers don’t know what it's miles and preserve this cost. Our experience is that maximum set up are walking on a speed that is lots too high for the application. When the speed is lower you can have longer cables and much less hazard of disturbances.

Question 74. Is It Necessary To Reconfigure The Bits & Bytes In The Control System When A New Device Is Added To Profibus?

Answer :

When a PROFIBUS device is added in the manipulate machine configuration, the device gets new reminiscence area assigned, which does NOT war with the prevailing configuration. The current configuration and application does not want to be touched.

Question 75. How Is The Term? Plug And Play? Used In Profibus?

Answer :

It has a double meaning; in case you replace a device with the same type it works immediately, because the configuration is saved within the control gadget. Also, you may without difficulty integrate a new device for your configuration with the aid of uploading a GSD report and synchronizing the cope with of the device. By serving standardized and profile based totally device descriptions PROFIBUS additionally allows a manufacturer impartial device substitute.

Question seventy six. Does Profibus Dp Have Self Triggered Alarms/diagnostics?

Answer :

When a tool has diagnostics it shows this all through the statistics change. The grasp will without delay fetch the diagnostics and makes the records to be had for the give up-consumer. The diagnostics from devices are absolutely event precipitated. Diagnostics are vital for easy and reliable operation. Devices record their own tool reputation and suggest when they need carrier. This reduces renovation prices and can boom time among scheduled field visits.

Question 77. A Pa Device Has At Least 3 Function Blocks. What Are These Blocks And What Is Their Purpose?

Answer :

In the system industry it's far commonplace to apply blocks to describe the traits and capabilities of a measuring/manipulation point and to symbolize an application via a mixture of these blocks. The specification of PA devices makes use of this characteristic block model to offer functional sequences.

Physical Block (PB):

Describes the essential parameters and capabilities of the device itself (e.G. Software version, serial variety, vendor ID, manufacturing unit reset command). There is only one Physical block in a PA device.

Transducer Block (TB):

Contains parameters which have impact or describe the type of sensor or actuator. Transducer blocks might also comprise parameters for calibration and linearization. The processed information is surpassed directly to the Function Block. If a device has greater sensors, it has corresponding Transducer Blocks for every sensor.

Function Block (FB):

Contains one or more cyclically accessible inputs or outputs parameters (system values). These can be of analog or discrete nature. Other parameters: setup scaling, alarms and unit factorization.

Question 78. What Is A Profile Within Profibus Pa?

Answer :

Modern PA devices are clever and can execute part of the records processing in automation systems. This turned into formerly accomplished by the PLCs or DCS structures. The PA profile is designed with co-operation of the procedure industry and defines all features and parameters for extraordinary lessons of devices. It is primarily based on across the world established function block era.

The profile carries descriptions for the subsequent device kinds:

Pressure (and differential)
Level, temperature and go with the flow
Analog/virtual inputs and outputs
Valves and actuators
Analyzers
The profile is split into 2 training (A and B):

Class A of the profile describes common parameters of simple devices. The scope is restrained to the simple capabilities. This set consists of the system variables (e.G. Temperature, pressure, degree) delivered by using measured value kingdom, the tag name and the engineering unit.

Class B is an extension to elegance A and will cover more complex utility features for identity, commissioning, protection and prognosis. The dating of the parameters to the classes is seen inside the parameter definitions and in the conformance statements.

To finish: The PA profile defines cyclical information + popularity, diagnostic information and parameters. The PA profile assures interoperability and device exchangeability

Question 79. What Is A Profile Ident Number?

Answer :

In instances wherein the tool of producer-A have to be replaceable through an equivalent tool of manufacturer-B, the same old Ident Number is not sufficient because a GSD document is associated with this quantity. When the tool is replaced a exchange in the configuration is vital a good way to cause a DCS/PLC stop. Therefore the PNO has assigned number degrees to dedicated device kinds (Profile Ident Numbers) in aggregate with positive Profile GSD documents. A device can assist a couple of Ident Numbers that are set by way of a parameterization tool. The give up-user has to determine whether or not to choose the Manufacturer particular Ident Number or the Profile Ident Number.

Examples:

Transmitter 0x9700 to 0x970F
Actuator 0x9710 to 0x971F
Discrete input 0x9720 to 0x972F
Discrete output 0x9730 to 0x973F
Question eighty. How Can You Measure The Length Of A Pa Segment?

Answer :

This is nearly impossible. Because of junction containers, spur lines and the input resistance of the gadgets it's miles very tough to do. At the instant there may be no device available.

Question 81. Are All Profibus Devices Certified?

Answer :

NO, it's miles NOT mandatory for a manufacturer to have a PROFIBUS master or slave certified. It is particularly recommended, because in maximum projects handiest licensed devices are decided on. At the moment best masters and slaves can be licensed. For connectors, cable and repeaters there are no certification guidelines available.

Remark: PROFIsafe and PROFINET gadgets should be licensed.

Question 82. In Which Standard(s) Is Profibus Specified?

Answer :

The PROFIBUS communication is laid out in IEC 61158 Type 3 and IEC 61784. IEC 61158 Type three consists of the entire variety of PROFIBUS, which includes the versions DP-V0, DP-V1 and DP-V2. IEC 61784 specifies the residences of the Communication Profile Family CPF three which is PROFIBUS. Additionally, the IEC published the “Corrigendum half/3” and “Implementation Guideline” associated with the above noted files. The Documents may be bought from the IEC internet site.

Question eighty three. What Is The Cost Comparison Between Conventional And Profibus Cabling?

Answer :

It is a common reality that PROFIBUS reduces cable expenses lots, but there is a extra that incorporates it:

Reduction of cable trays
Energy financial savings
Less documentation
Better assessment
Reduction of take a look at time
Less spare parts
Easy to enlarge or change
Shorter downtimes due to short repair
Easy to dismantle
This is best infrastructure and the initial financial savings. But the actual cash making starts offevolved with the renovation and the operational costs. PROFIBUS is an first rate preference, but some training is required to get awareness about the benefits.

Question eighty four. Is Profibus A Single Or Multi-protocol Technology?

Answer :

Within PROFIBUS there is most effective one communication layer implemented that is; PROFIBUS DP. Based in this verbal exchange layer, numerous device profiles are defined in the application layer. These profiles provide not unusual information, diagnostics and parameters for the end-person. Sometimes human beings are confused with PROFIBUS DP and PA, however the handiest difference is the physical interface. In reality, a PROFIBUS PA device is a PROFIBUS DP tool with an software profile ideal for the technique industry.

Question 85. Can Profibus Meet The Requirements For Fast Communication Speed And Does It Have A Longer Message Length Compared To Other Buses?

Answer :

PROFIBUS can run on 12 Mbps, which makes it the quickest fieldbus within the international. The messages have most effective 9 bytes overhead which makes it very efficient. An set up with 30 gadgets will have a cycle time of less than 1 ms. PROFIBUS is the choice for instant message shipping within the commercial automation environments.

Question 86. What Makes Profibus Unique In Terms Of Cycle Time, Real-time Behavior And Diagnostics?

Answer :

PROFIBUS and PROFINET have the fastest cycle time, which may be much less than 1 ms. This cycle time is extremely solid which makes it Real-Time. For diagnostics we have standardized formats and protection gear that healthy flawlessly with the demands that renovation personal has.

Question 87. What Are The Benefits Of Profibus For The End-users Compared To Other Systems?

Answer :

First of all PROFIBUS is the simplest fieldbus that may be used in all parts of the manufacturing unit (upstream, procedure and downstream). This approach you could use 1 sort of manipulate device, 1 expertise bundle, 1 institution of spare components and 1 design method.

PROFIBUS also has a completely large range of manufacturers presenting products and services. This way for nearly every utility there is solution and enough backup merchandise available. These products additionally have strengths in certain application areas such as; motion manage or process manage. PROFIBUS has test labs that certify products. PROFIBUS guarantees that each product constantly works with products from other manufacturers.

PROFIBUS has Competence Centers that assist the give up-users with their automation questions and closing but no longer least, Certified Training Centers offer education. People from the running groups are operating near together to create a better global thinking about the cost issue and the environment. They have a special band! Different people from special groups can work together with out political, commercial enterprise and personal barriers. All faces pointing to the equal path and we get the job completed! The end result in their difficult work is that; PROFIBUS and PROFINET can prevent electricity, weight, materials, spare elements, documentation and lots of attempt.

Question 88. Is There An Open Source Implementation Of Profibus Available?

Answer :

PROFIBUS is an open specification. Every company is permitted to create a grasp/slave implementation. Some patents are applicable to the PROFIBUS DP specification. The patent holders have granted freed from rate licenses to all members of any RPA. Non-members have to agree on a license with the patent holders.

If a enterprise wants to release a PROFIBUS implementation (software or hardware) as an open-source solution, the rules are relevant that are agreed on the OSADL (Open Source Development Lab, see www.Osadl.Org). These policies say that no implementation may be released as an open-supply solution if it's miles covered by patents. This approach that neither a PROFIBUS DP slave nor master can be registered as an open supply implementation.