Read the frequently asked Profibus Communication Interview Questions & Answers useful for Automation Engineers, PLC Engineers, DCS Engineers.
PI was formerly know as PROFIBUS International. It is the umbrella organization responsible for the PROFIBUS protocol and its promotion and support across the world via a network of Regional PI Associations.
When PROFINET, PI’s Industrial Ethernet solution, was launched, PROFIBUS International was re-named ‘PI’ (PROFIBUS and PROFINET International).
It is recommended to connect the shield on both ends low inductively to ‘ground’ in order to achieve optimal electromagnetic compatibility. In the case of separate potentials (e.g. in a refinery) the shield should be connected only on one end of the cable to ‘ground’.
Preferably, the connection between shield and protective ground should be made via the metal cases and the screw top of a D-sub connector. If this is not possible the connection can be made via pin 1 of the D-sub connector. It should be noticed that this is not the optimal solution.
In such a case it is better to bare the cable shield at an appropriate point and to ground it with a cable as short as possible to the metallic structure of the cabinet. This can be done with a ground bus bar in front of the bus connector.
This is the performance optimized version of PROFIBUS, specifically dedicated to time-critical communication between automation systems and distributed peripherals.
It is suitable as a replacement for the costly parallel wiring of 24 V and 4(0) to 20 mA measurement signals. PROFIBUS-DP is included into the European Fieldbus Standard EN 50170.
Every DP/PA device type has to have an individual ident Number. This number is necessary so that a DP-master is able to identify the types of the connected DP/PA devices without a significant protocol overhead. The master compares the ident Number of each connected device with the ident Number in the configuration database.
User data transfer in the operation phase is only possible when the right DP Slave is connected to the correct address. This ensures very high protection against parameterization faults. The vendors must apply to the PPROFIBUS Support Center for an individual ident Number for every DP/PA device type.
PROFIBUS-PA is a ‘profile’ of PROFIBUS designed specifically for use in process automation for connecting control systems with field instruments. PROFIBUS-PA is based on PROFIBUS-DP and, using a linking device called a segment coupler, permits transparent communication between general purpose automation and process automation networks, making PROFIBUS ideal for hybrid applications where factory and process devices intermingle.
The PROFIBUS PA profile defines the behavior of the field devices and ensures full interoperability and interchangeability between different manufacturers. PROFIBUS PA operates either with Intrinsically Safe transmission technology (acc. to IEC 61158-2) or standard transmission technology (acc. to RS485).
PROFIBUS is based on recognized international standards. The protocol architecture is oriented to the OSI (Open System Interconnection) reference model in accordance with the international standard SO 7498.
In this model every transmission layer handles precisely defined tasks. Layer 1 (physical layer) defines the physical transmission characteristics. Layer 2 (data link layer) defines the bus access protocol. Layer 7 (application layer) defines the application functions.
The architecture of the PROFIBUS protocol is shown in figure.
PROFIBUS-DP uses layers 1 and 2, and the user interface. Layers 3 to 7 are not defined. This streamlined architecture ensures fast and efficient data transmission. The Direct Data Link Mapper (DDLM) provides the user interface easy access to layer 2.
The application functions which are available to the user as well as the system and device behavior of the various PROFIBUS-DP device types are specified in the user interface. RS 485 transmission technology or fiber optics are available for transmission.
In PROFIBUS-FMS, layers 1, 2 and 7 are defined. The application layer consists of FMS (Fieldbus Message Specification) and LLI (Lower Layer Interface).
FMS contains the application protocol and provides the user with a wide selection of powerful communication services. LLI implements the various communication relationships and provides FMS with device-independent access to layer 2.
Layer 2 (FDL, Fieldbus Data Link) implements bus access control and data security. RS 485 transmission technology or fiber optics are available for transmission for PROFIBUS-FMS.
PROFIBUS-PA uses the extended PROFIBUS-DP protocol for data transmission. In addition, the PA profile, which defines behavior of the field devices, is used.
Transmission technology, in accordance with IEC 1158-2, permits intrinsic safety and also allows the field devices to be powered over the bus. PROFIBUS-PA devices can be easily integrated in PROFIBUS-DP networks using segment couplers or Links.
PROFIBUS-DP and PROFIBUS-FMS use the same transmission technology and a uniform bus access protocol. Thus, both versions can be operated simultaneously on the same cable.
Profibus or process field bus is digital industrial communication system that use physical mediums such as optical fiber or copper cable for data exchange.
1. Profibus FMS
2. Profibus DP
3. Profibus PA
4. Profi-Drive
5. Profi-Safe
Profibus FMS (field messaging system) is an obsolete now. Honestly i don’t know much about it.
Profibus DP (Decentralized Peripheral ) is used for interfacing PLC’s, Remote IO Systems, Variable Frequency Drives, HMI’s, Encoders, Sensors, Actuators and other similar devices. It uses RS 485 technology . As of now DP V-2 is the latest version.
Profibus PA (Process Automation) is used for interfacing field measuring devices such as flow transmitters, pressure transmitters etc. It uses Manchester Coding technology.
Profi-Drive is used for motion control applications (Controlling of Servo motors in position control mode).
Profi-Safe is used for Fail Safe applications.
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, yet still match the checksum calculations, in order for it to be mistaken as a valid packet.
Termination of the bus prevents signal reflections on the PROFIBUS cable. Wrong or missing termination results in transmission errors when the worst case result is that the communication link is lost.
In addition, the PROFIBUS termination provides a defined ‘idle’ level for the cable.
Profiles are definitions of non-mandatory services and parameters for specific areas of applications.
It helps to minimize the implementation efforts to implement PROFIBUS functionality in appropriate field devices.
This is a subjective issue but – provided that the technical solution is satisfactory for the task – it boils down to cost/benefit comparisons.
PROFIBUS provides users with the best possible, future proof bus system that can cope with the broad needs of factory and process automation. Market acceptance and sheer momentum means that PROFIBUS is a de-facto fieldbus standard throughout the world.
Also Read: HART Communication Interview Questions & Answers
A Class 1 master can communicate actively only with its configured slaves and is able to communicate in a passive way with a Class 2 master. The class 2 master is the ‘supervisory’ device.
It can communicate with Class 1 masters, their slaves and its own slaves for configuration, diagnostic and data/parameter exchange purposes.
This mode defines the status of signals in IO modules if a bus or system failure occurs. It is common that all output signals are going to the zero voltage level in a fail safe situation.
The status is important in functional safety applications where a profile such as PROFIsafe is used.
To ensure easy handling a signal ‘ground’ wire is not used by PROFIBUS.
However, it is recommended to isolate the interface circuit from the local ground (e.g. using opto-couplers) to reduce possible common mode voltages between transceivers.
PROFIBUS is completely open. It was originally standardized in Germany in 1989 as DIN 19245 and in July 1996 as EN 50 170.
The EN 50 170 specification is available through any of the national standards bodies of CENELEC / IEC and the PROFIBUS Specification can be supplied by any of the Regional PROFIBUS Associations. It’s now globally standardized under IEC 61158.
Not generally but PROFIBUS connectivity should not add significantly to standard field device costs as most devices today are digitally based anyway. It’s more instructive to look at wider issues.
Having a single cable to connect devices means big savings in design, engineering and installation costs. Furthermore, the availability of data across the plant means even more savings are possible over the lifetime of a device through better operations and improved asset management.
Better data flows lead to better plant management too. Overall, any extra cost per device is insignificant compared with the life cycle savings of a fieldbus network.
A GSD file is used to identify the basic operational characteristics of a PROFIBUS device, to aid interoperability and interchangeability.
It makes it possible to have manufacturer-independent configuration tools. Typically, a GSD file includes vendor information, baudrates, timing information, the options or features supported and the available I/O signals.
A GSD file must be available for every PROFIBUS slave.
The base of the specification of the PROFIBUS standard was a research project that took place between 1987-1990, supported by the following companies: ABB, Phoenix Contact, AEG, Rheinmetall, Bosch, RMP, Honeywell, Sauter-Cumulus, Kloeckner-Moeller, Schleicher, Landis & Gyr, Siemens.
Five German research institutes also cupported the project: FZI Karlsruhe, LRT, IITB, WZL, LPR
There was also minor sponsorship from the German government.
The result of the project was the first draft of DIN 19245, the PROFIBUS standard.
PROFIBUS has been designed to allow configurations where redundant cabling is possible to take account of wire breaks. Also, node failures can be configured to be ignored, or to trigger a ‘stop’ in the master.
In this case unaffected nodes can continue operation. When a failure is identified the master immediately resends the telegram and it’s possible to configure the number of times this is attempted.
Information relating to the failure is generally available on a node, a module within a node and on a channel specific basis.
Certification testing of devices through an authorized test laboratory ensures that potential failures conform to what is expected of them. Media redundancy can be achieved through dual master systems.
PROFIBUS guarantees backwards compatibility. So, if new functions are offered in a device it will still be possible to use this device on the same wire with older devices, allowing progression of the system without forcing users to upgrade unless they specifically wish to enhance their functionality.
In addition to a PLC and the devices to be controlled
The PROFIBUS Standard does not specify an alternative to the 9 pin D-SUB connectors, but it is often necessary to have alternatives available.
PROFIBUS has already found many applications in factory, process and building automation, for example from Automotive manufacture at General Motors across Europe, to Breweries like Bitburger and Guinness to building management like the Russian Kremlin building.
PROFIBUS is also being used in applications that were never envisaged from its conception, because it has been constructed in a way that allows for many new device types to be added.
However, the two key areas of industry that can most benefit from its adoption are :
The PROFIBUS standard defines two variations of the bus cable. However it is recommended to use cable Type A in all new installations.
Type A is recommended for high transmission speeds and permits a doubling of the network distance in comparison to Type B.
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 a master/slave architecture, specialized “Profiles” are used to support each of these areas. Several messaging could be added over PROFIBUS:
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.
PROFIBUS PA (Process Automation) is used to monitor measuring equipment via a process control. PA has a data transmission rate of 31.25 kbit/s.
However, PA uses the same protocol as DP, and can be linked to a DP network using a coupler device (Gateway/link).
PROFIBUS PA could be used in intrinsically safe and non intrinsically safe sector. It provides a solution to provide power via the bus.
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
With Profibus DPV0 and DPV1, two communications types are available:
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.
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.
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.
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.
S7 is a messaging allowing to communicate 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) MEMEMTO, 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.
PROFIBUS is based on a Token principle with underlying Master/ Slave communication (hybrid media access).
Services:
PROFIBUS allows up to 32 nodes per segment and up to 126 nodes for one network.
The base technology is a line which allows connection and removal of nodes at any time without breakdown.
PROFBUS allows ring and star topology as well with fiber optics.
The maximum distance would be 1000m by using copper with baudrates between 9.6 – 187.5 kBaud.
The maximum length may be extended with fiber optic links (up to 2300/15000 m per link)
PROFIBUS allows between 0 and 244 byte, determined by the device requirements for input and output each.
There is no specialized bus power supply. The terminal resistors with pullup 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.
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).
Two methods are supported:
Any choice is possible
Configuration checks for duplicate addresses.
Masters will look for duplicate addresses before entering the token ring and when unexpected frames are received.
Slave must be set up with their ident-number and with their configuration. In case of a mismatch, this will be reported to the masters application.
Yes, with the function config_check after power up. In addition, the ident number is also checked.
There are several ways for parameter setup:
This is determined by the device, the minimum would be one byte.
The protocol efficiency may be up to 70%.
The configurations mentioned in the performance metrics section have a efficiency of 40%. This figures are configuration dependent.
DP extensions may use the same link and may be implemented in one node
Several diagnostic tools are available which allow to measure the bus and connectors for proper installation.
A simple electric meter will do it for most cases (a segment unpowered has a resistance of 110 to 130 Ohms for mid range cable length).
Every PROFIBUS Master allows detailed diagnostic function within the application
Network download protocol is defined in the standard
Some System have proprietary protocols to prevent inconsistencies (network configuration and PLC configuration are NOT independent)
Various configuration tools offer such a functionality as well the bus monitor.
Most users look on reaction time rather than cycle time which includes the PLC scan.
PROFIBUS allows replacing of devices without interrupting the bus traffic to connected nodes.
Slave devices need not be reconfigured in case of a switching in the masters role.
The best case which is 99% the normal case is that the timing is absolute stable (5% jitter is possible due to control functions)
In case of a failure (stations are dropping out) the timing can change
1 transmission failure will be corrected within 500/100μs (1,5/12Mbaud)
1 station failure will add a jitter of 700/300μs
A worst case scenario of 33ms by 1.5MBaud or 6.6ms by 12MBaud for one cycle will occur when all stations fail (in this situation the reactiontime is meaningless).
After the failure detection the timing is back to the regular cycle time.
It is exactly the same time as under 1., PROFIBUS makes no difference in the format. 256 words is equal to 4096 I/O points. I’m assuming that we have 256 words in each direction, 256 input words and 256 output words.
A difference can occur in your master station. The PLC or PC might make a difference in calculating I/O or analog values. PROFIBUS makes no difference.
There is a transmission speed detection in almost every slave device as well as repeaters. This will enable the user to change the Baudrate by simply changing it at the masters site.
PROFIBUS has enhanced transmission speed 2 times. there is no problem with the various devices because all functions may run at a basic configuration.
A change of the cyclic list is possible, however due to the fast cycle it is not necessary in typical applications. There is a possibility to send low frequent cyclic messages as acyclic messages.
PROFIBUS defines 2 message priorities, an application prioritization is only possible within FMS.
Yes, with all protocols.
Deterministic, speed, ease to use, acceptance, support, diagnostic, multi protocols.
PROFIBUS offers a great flexibility. This enables the application engineer to make his design without counting bits and bytes. One byte more is less than 1μs! Error recovery will be done quickly without user interaction.
It easy to integrate PROFIBUS in field devices.
PROFIBUS is a very robust protocol with outstanding error handling capabilities.
PROFIBUS-DP allow transmission of IO-Data with short reaction time this include transportation from IO to the bus and from the bus to the application.
PROFIBUS-DP can be configured without specific communication knowledge. The device model is exactly what matters in remote IO.
PROFIBUS DP is what the user needs mostly.
A short-circuit at the PROFIBUS cable can disturb a data communication in the particular segment. The devices in that area will NOT get damaged!
The short-circuit can easily be detected with an oscilloscope and even the distance to the problem can be masured. If the end-user wants to keep the installation running during a short-circuit he can pick the following solutions:
A lot of people are aware that termination has to be powered and activated at both ends of the cable. What they do not know, is that it has to be activated again when you are using repeaters, OLMs or Profihubs.
Every segment has to be terminated! This often slips in when people are using lots of fibre optic and there is only a short length of copper cable in the cabinets. Even this short cable has to be terminated at both ends.
The input resistance of the diagnostic plugs is approx. 1,5..2,0 M Ohm (analog comparator input). This is 100 times higher as the RS 485 receiver input impedance. In theory this should not cause any problems which have not been detected so far.
There are lots of stories out there concerning this subject. The actual answer lies in the electronic components of the repeater. These determine the actual “maximum number?
The digitalization from and to the opto-couplers in 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 recognized anymore. There are also repeaters available with no limit in serial placement.
Check the manual of the repeater! It should state the maximum amount. For example: the Siemens repeater is 9, the ProfiHub is unlimited.
The second step is changing the busparameters. All repeaters have a delay time. If you put a large quantity of repeaters in series you might have to change the Tslot busparameter to a higher value.
Termination prevents reflections that can disturb the data communication. The higher the baudrate and the longer the cable, the more important termination becomes.
Termination should be activated/placed at both ends of every bus segment. With PROFIBUS DP the termination is powered to provide an idle level when nobody is sending data.
With PROFIBUS PA the termination is a combination of a resistor and a capacitor.
YES, even PROFIBUS can get disturbed by interference caused by parallel high voltage power lines. Always try to have at least 10 cm air space between the cables (depends on the level of the voltage).
Most users mix all cables in one cable tray and that often leads to unreliable behavior. Cables that cross each other will not cause problems. Creating distance is not the only requirement. Correct shielding is also a must!
Lots of users have the impression this will never cause a problem because of the high speed signal characteristics of DP cable (even if the impedance is not correct), but there are other factors that could make it very unstable
Our advice is to use only cable that complies with the PA specifications!
When the transmission speed is 1,5 Mbps or higher, it is highly recommended to have at least 1 m of cable between 2 devices. De input capacitance of both devices will be compensated by the cable in order to preserve the common impedance.
When the devices would be very close together, there is a big chance the input capacitance causes reflections in the data communication (small short circuits). The effect is much less at transmission speeds lower than 1,5 Mbps.
NO, because of certain application, protection and isolation classes, PROFIBUS DP cable can have another colour. Example: ground cable and shipboard cable are black, robust cable is green. The standard cable is always violet!
Yes, multiple (parallel) Profibus cables can be installed in a metal conduit. It gives good behaviour when EMC is involved.
1.5 Mbps is the most commonly used transmission speed. This is the default speed when you create a new project. Most users don’t know what it is and keep this value.
Our experience is that most installation are running on a speed that is much too high for the application. When the speed is lower you can have longer cables and less chance of disturbances.
When a PROFIBUS device is added in the control system configuration, the device gets new memory space assigned, which does NOT conflict with the existing configuration.
The existing configuration and program does not need to be touched. This makes PROFIBUS perfect for ?instrument expansion? or ?complete machine copying?.
It has a double meaning; if you replace a device with the same type it works directly, because the configuration is stored in the control system.
Also, you can easily integrate a new device in your configuration by importing a GSD file and synchronizing the address of the device.
By serving standardized and profile based device descriptions PROFIBUS also enables a manufacturer independent device replacement.
When a device has diagnostics it indicates this during the data exchange. The master will immediately fetch the diagnostics and makes the information available for the end-user.
The diagnostics from devices are completely event triggered. Diagnostics are important for smooth and reliable operation. Devices report their own device status and indicate when they need service. This reduces maintenance costs and can increase time between scheduled field visits.
In the process industry it is common to use blocks to describe the characteristics and functions of a measuring/manipulation point and to represent an application through a combination of these blocks. The specification of PA devices uses this function block model to present functional sequences.
Describes the necessary parameters and functions of the device itself (e.g. software version, serial number, vendor ID, factory reset command). There is only one Physical block in a PA device.
Contains parameters which have effect or describe the type of sensor or actuator. Transducer blocks may also contain parameters for calibration and linearization. The processed information is passed on to the Function Block. If a device has more sensors, it has corresponding Transducer Blocks for every sensor.
Contains one or more cyclically accessible inputs or outputs parameters (process values). These can be of analog or discrete nature. Other parameters: setup scaling, alarms and unit factorization.
Modern PA devices are intelligent and can execute part of the information processing in automation systems. This was previously done by the PLCs or DCS systems.
The PA profile is designed with co-operation of the process industry and defines all functions and parameters for different classes of instruments. It is based on internationally accepted function block technology.
The profile is divided into 2 classes (A and B):
Class A of the profile describes common parameters of simple devices. The scope is limited to the basic functions. This set consists of the process variables (e.g. temperature, pressure, level) added by measured value state, the tag name and the engineering unit.
Class B is an extension to class A and will cover more complex application functions for identification, commissioning, maintenance and diagnosis. The relationship of the parameters to the classes is visible within the parameter definitions and in the conformance statements.
To conclude: The PA profile defines cyclical data + status, diagnostic information and parameters. The PA profile assures interoperability and device exchangeability
In cases where the device of manufacturer-A should be replaceable by an equivalent device of manufacturer-B, the standard Ident Number is no longer sufficient because a GSD file is associated with this number.
When the device is replaced a change in the configuration is necessary which will lead to a DCS/PLC stop. Therefore the PNO has assigned number ranges to dedicated device types (Profile Ident Numbers) in combination with certain Profile GSD files.
A device can support multiple Ident Numbers which are set by a parameterization tool. The end-user has to decide whether to select the Manufacturer specific Ident Number or the Profile Ident Number.
This is almost impossible. Because of junction boxes, spur lines and the input resistance of the devices it is very hard to do. At the moment there is no tool available.
NO, it is NOT mandatory for a manufacturer to have a PROFIBUS master or slave certified. It is highly recommended, because in most projects only certified devices are selected.
At the moment only masters and slaves can be certified. For connectors, cable and repeaters there are no certification guidelines available. Remark: PROFIsafe and PROFINET devices must be certified.
The PROFIBUS communication is specified in IEC 61158 Type 3 and IEC 61784. IEC 61158 Type 3 includes the entire range of PROFIBUS, consisting of the versions DP-V0, DP-V1 and DP-V2.
IEC 61784 specifies the properties of the Communication Profile Family CPF 3 which is PROFIBUS.
Additionally, the IEC published the “Corrigendum 1/2/3” and “Implementation Guideline” related to the above mentioned documents. The Documents can be purchased from the IEC website.
It is a common fact that PROFIBUS reduces cable costs a lot, but there is a more that comes with it:
This is only infrastructure and the initial savings. But the real money making starts with the maintenance and the operational costs. PROFIBUS is an excellent choice, but some training is required to get awareness about the advantages.
Within PROFIBUS there is only one communication layer implemented which is; PROFIBUS DP. Based on this communication layer, several device profiles are defined in the application layer.
These profiles provide common data, diagnostics and parameters for the end-user. Sometimes people are confused with PROFIBUS DP and PA, but the only difference is the physical interface.
In fact, a PROFIBUS PA device is a PROFIBUS DP device with an application profile suited for the process industry.
PROFIBUS can run on 12 Mbps, which makes it the fastest fieldbus in the world. The messages have only 9 bytes overhead which makes it very efficient.
An installation with 30 devices can have a cycle time of less than 1 ms. PROFIBUS is the choice for fast message delivery in the industrial automation environments.
PROFIBUS and PROFINET have the fastest cycle time, which can be less than 1 ms. This cycle time is extremely stable which makes it Real-Time.
For diagnostics we have standardized formats and maintenance tools that match perfectly with the demands that maintenance personal has.
First of all PROFIBUS is the only fieldbus that can be used in all parts of the factory (upstream, process and downstream). This means you can use 1 type of control system, 1 knowledge package, 1 group of spare parts and 1 design strategy.
PROFBUS also has a very large number of manufacturers offering products and services. This means for almost every application there is solution and enough backup products available.
These products also have strengths in certain application areas such as; motion control or process control. PROFIBUS has testlabs that certify products. PROFIBUS guarantees that every product always works with products from other manufacturers.
PROFIBUS has Competence Centers that support the end-users with their automation questions and last but not least, Certified Training Centers provide training. People from the working groups are working close together to create a better world considering the cost aspect and the environment.
They have a special band! Different people from different companies can work together without political, business and personal barriers. All faces pointing to the same direction and we get the job done! The result of their hard work is that; PROFIBUS and PROFINET can save you energy, weight, materials, spare parts, documentation and a lot of effort.
PROFIBUS is an open specification. Every company is allowed to create a master/slave implementation. Some patents are relevant to the PROFIBUS DP specification.
The patent holders have granted free of charge licenses to all members of any RPA. Non-members have to agree on a license with the patent holders.
If a company wants to release a PROFIBUS implementation (software or hardware) as an open-source solution, the rules are relevant that are agreed at the OSADL (Open Source Development Lab, see www.osadl.org).
These rules say that no implementation can be released as an open-source solution if it is covered by patents. This means that neither a PROFIBUS DP slave nor master can be registered as an open source implementation.
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