Profibus implementation

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Thread Starter

Brandon Ellis

My company is a mfg. of a plug-n-play multi-axis motion system.
Presently we are looking into implementing Profibus. I am having trouble finding out what this involves. I know many mfg.'s support Profibus, but does it require a license or is it non-proprietary? Whatever the case, where do I go to get it (the license or the breakdown).
I know (at least I think I know) that Siemens was responsible for inventing Profibus; however,
when I do a web search, Siemens doesn't even come up. Can anyone help?

p.s. BONUS QUESTION: Does anyone know of an existing communications board which supports
most/all of the CAN bus protocols (i.e. Profi, Devicenet, Modbus, MB+, etc.)?

Thanks in advance!

-Brandon
 
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Kai Atle Myrvang

Hi!

PROFIBUS is a part of EN50170 and IEC61158, and you can find more than enough tech info in those standards.

PROFIBUS is then without license, but if you choose to base your development on someone's toolkit/software stack, there is a price.

The basis for PROFIBUS is from a German reseach project, where many companies was involved, Siemens being one of them.

PROFIBUS is NOT CAN-based....but for some 'generic' solutions look at www.anybus.com, www.hilscher.com and surely there are others.

For more PROFIBUS information, look at www.profibus.com

regards,

Kai Atle Myrvang

AD Elektronikk AS, Oslo, Norway
 
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Brandon,

Last question first. The two "open" CAN protocols that are commonly used in automation are DeviceNet and CANopen. There are others, but I'm not sure of the market size. Most cards available for these protocols will support either, depending on the software you run with them. Profibus is RS-485 (multidrop) technology, as is (I believe Modbus). MB+ I'm not sure of, as
we haven't implemented, but I think at least the version that runs on coax is transformer coupled like Ethernet or Arcnet. Anyway, one of the easiest ways to implement different bus architectures is to use the HMS Anybus cards; they have a common dual-port RAM interface and are available for all commonly used industrial protocols. The boards are approximately 2"x 3",
and have everything you need including connectors and firmware. See www.hms.se. There are distributors in most countries.

There's not a license per se to implement Profibus. However, you should probably join the Profibus Trade Organization. You can talk to Michael Bryant at +1.480.483.2456 to find out about that, or visit the PTO website
(www.profibus.com). This will help you with information and conformance testing. This testing can be done in either the US or Germany.

I know you didn't ask about this, but it may save you some time--as far as Profibus hardware implementation, there are a couple of different ways to go. There are ASIC chips to implement Profibus-DP, with or without a microprocessor. I will assume you need a microprocessor interface. In this case, you can use the SPC3 chip from Siemens. This chip is second-sourced.
You also need a software stack for this chip, also available from Siemens for less than $2,000. There is also a Dutch company that has a stack for a little less money. Let me know if you need their URL, and I will dig through old e-mails to find it. In either case, it should not be hard to
port the code to your target. I think it took us a few days for the Siemens stack. This is the only "license" you need.

Another option is to use the MC68360 controller from Motorola. They have microcode that implements Profibus-DP within the serial communication controller. I don't know if there is a charge for this code; perhaps you
could check the Mot website if you need this much processing power for other things in your application. See www.mot.com.

It is possible to implement DP with (say) an 8051 and a serial port. However, it will take all the power of an 8051 to implement DP, and I doubt
if you could make it work over 500KBPS. I think there are some companies in Germany that sell stacks like this.

If you have any other questions, I'll be happy to answer either on- or off-line.

Regards,

Willy Smith
Numatics
Costa Rica
 
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Heinz-Juergen Oertel

Most CAN interface cards do support the most HLP Higher Layer Protocols for CAN.
HLP's are sitting on top of OSI-Layer 2 CAN, and this is what CAN controllers support in hardware.
Differences exist in cabling and connectors. But in this case adapters can be used.

You can have parts of the HLP's running on the interface board. In this case computing power is required and the boards are more expensive.
Also in this case it is possible that one board is not supported by all HLP's.

I can imagine that interfaces exist which support field busses with different physical interfaces (layer-2) like CAN, Profibus or Modbus or whatever, but they will be rare.

with best regards / mit freundlichen Gr=FC=DFen

Heinz-J=FCrgen Oertel
port GmbH phone +49 345 77755-0
Regensburger Str. 7c fax +49 345 77755-20
D-06132 Halle/Saale mailto:[email protected]
Germany http://www.port.de
 
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Curt Wuollet

Hi Brandon.

Just a note, I don't believe ProfiBus or MB/MB+ is built on CAN. Someone else provided the URL's.

Regards
cww
 
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Willy Smith wrote:

> Profibus is RS-485
> (multidrop) technology, as is (I believe Modbus). MB+ I'm not sure of, as
> we haven't implemented, but I think at least the version that runs on coax
> is transformer coupled like Ethernet or Arcnet.

Profibus and Modbus are both RS485 based. Most profibus users are actually using profibus DP, which is a protocol that passes a set of data tokens round a network for sharing data. Modbus implementations are master-slave requests like profibus FMS, MB+ adds the DP like functionaility to Modbus. Put another way, although each is capable of doing each others job, TYPICAL usage is different. In TYPICAL usage, profibus requires a custom ASIC or a dedicated processor to implement an interface, whilst modbus can be used via a normal serial port. Also, modbus is
capable of being used over modems, and an extension allows its usage over TCP/IP which basically means you can use it over just about any media from ethernet though to radio links and, of course, the internet. Profibus DP is not very suitable for TCP/IP because it is basicly designed to be syncronous whilst TCP/IP is asynchrous (in this context sync/async refers to the data packets, not the bit clock).

Note also that systems using Modbus or Profibus FMS type of protocolls require MUCH less bandwidth than profibus DP. In fact profibus DP is very bandwidth hungry and this severely limits its usage as it does not scale gracefully and the high bit rates used (1.5Mbits or even 12Mbits) put severe limits on cable length.

>
> It is possible to implement DP with (say) an 8051 and a serial port.
> However, it will take all the power of an 8051 to implement DP, and I doubt
> if you could make it work over 500KBPS. I think there are some companies in
> Germany that sell stacks like this.

Years ago (Hannover 94) I saw a 20MHz 8051 doing a DP slave. One would assume that more recent evolutions (for example a DALLAS @ 40MHZ) would be able to do a DP slave with less than 1/3 overhead, and still be compatible with the 8051 stacks.
 
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Andrew Piereder

You might want take a look at Universal Communication System, UCS by SST. The system features a common board level interface to a small daughter card that allows a manufacturer to simply plug in the appropriate network
personality. The system includes software to customize an electronic data sheet (.GSD for Profibus)for each network you are interested in. I think the obvious advantage is that a single implementation of the USC interface allows a manufacturer to use a wide variety of network interfaces.

I believe they have customers using these cards in motion control products. Email mailto:[email protected] for more information.

Andy Piereder
Pinnacle IDC
 
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Rob Hulsebos Philips CFT

> > My company is a mfg. of a plug-n-play multi-axis motion system.
> > Presently we are looking into implementing Profibus. I am having
> > trouble finding out what this involves. ...<clip>
> >...
> > p.s. BONUS QUESTION: Does anyone know of an existing communications
> > board which supports most/all of the CAN bus protocols (i.e. Profi,
> > Devicenet, Modbus, MB+, etc.)?

Well such boards hardly exists as the hardware for all mentioned protocols is different.
And Profibus, Modbus, etc. are not "CAN".

Take a look at www.anybus.com for a company that goes a bit in the right direction.

Links for more info on the mentioned systems can be found at http://ourworld.cs.com/rahulsebos
(and 226 other systems as well in case you'd like to study a bit...)

Greetings,
Rob
 
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Rob Hulsebos Philips CFT

>> It is possible to implement DP with (say) an 8051 and a serial port.
>> However, it will take all the power of an 8051 to implement DP, and I doubt
>> if you could make it work over 500KBPS. I think there are some companies in
>> Germany that sell stacks like this.
>Years ago (Hannover 94) I saw a 20MHz 8051 doing a DP slave. One would assume that
>more recent evolutions (for example a DALLAS @ 40MHZ) would be able to do a DP
>slave with less than 1/3 overhead, and still be compatible with the 8051 stacks.

I not only saw that too but worked with it as well. The 8051 ran at only 16 Mhz, and could keep
up comfortably at 500 Kbit/s. The implementation was done in assembly and the last clock cycle
optimised out. This is of importance because of the requirement that there should be no "gap"
between the transmission of a stop bit and the start bit of the next byte. This may influence the
usage of a RTOS kernel. Nowadays, the hard real-time work is better left to a profibus asic
from Siemens or Profichip.

Rob Hulsebos
 
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