ControlLogix and Profibus DP/PA

Hello

I'm currently working on a project using AB ControlLogix (L61) and Profibus. We have 2 Prosoft DP scanners in the chassis and 2 separate Profibus networks each consisting of:

Flex I/O through Prosoft Profibus adapter.
Siemens DP/PA Coupler.
Approx 20 Profibus PA instruments (E+H) and actuators (Siemens Sipart).

I've fumbled my way through seting up the Flex I/O and managed to get it working OK. I haven't yet got my hands on any PA instruments, but hope to soon. I've got all the instrument manuals and GSD files.

Has anyone got any experience of this type of setup? Any pitfalls/limitations/advice?

Any help much appreciated.

Hello Keith;


The most important point you will have to take into account is the bus speed limitations imposed by the PA couplers (at least from Siemens);

Prerequisite​

The DP/PA coupler is ready to operate when you have installed and wired the DP/PA coupler completely and have switched on the power supply.​

Setting the transmission rate



​

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A transmission rate of 45.45 kBaud is to be set for the DP master.


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Click to expand...

(From the "Link couplers DP/PA link and Y link" pdf manual, on Siemens' support website)

As you are using the PA coupler, you insert the GSD file provided by the instrument manufacturer into the Profibus-DP configurator, and set them up as you would do any DP slave; but bus speeds supported by Profibus-PA are 31,35 kB on the PA side, and 45,45 (with Siemens coupler)or 93,75 kB (with P&F SK1/SK2 coupler) on the DP bus side.
If you can live with that bus speed (all of the other master/slaves must adapt to the lowest speed on the bus) then the simplest is to leave it at that.
If you require a better update time, I know of 2 ways:
- use a Siemens DP-PA link (IM153 + PA coupler)which allows bus speeds of up to 12 MB on the DP side, but requires additionnal work to generate a single GSD file for all the PA slaves on the PA side. There is an advantage in this: the DP-PA link counts as a single node on the Profibus-DP side; important depending on your network topology and number of DP slaves. Remember that a DP segment ends as soon as there are more than 31 slaves, even though you have not reached the maximum length of the bus at the speed you are using; you must then use a repeater. Another interresting possibility is that the DP-PA link can hold up to 5 PA couplers, and configure up to 64 PA slaves into the single SGSD file; so basically one DP node can be a connection poit to 64 PA slaves (we neever went above 42, until now).
There is a downloadable software from Siemens (GsdtooL.exe) that creates the final GSD for the DP-PA link, starting with the individual PA instrument GSDs.
- consider a P&F SK3 coupler, which allows up to 12 MB on the DP side without having to modify the GSD files of the instruments.

Hope this helps,
Daniel Chartier

Controllogix and Profibus

KeithB

How did the setup for Profibus with Controllogix go?

I just set up a controllogix with a SST/Brad Woodhead Profibus DP scanner. I currently am connected to flex I/O. I also stumbled through the setup. My biggest issue was that you have to configure all 18 slots to get the scanner to talk to flex. The slots that are not used are configured as empty. Then you have to get the scanner from "clear" mode to "run" mode to get the outputs to work. There is a command in the scanner to accomplish this. In "clear" mode all of the outputs are disabled. It must be some kind of safety feature.

My next step is to configure two Powerflex drive with DP ports. Then comes the PA.

Did you get the PA to work yet?

Hi

The setup went well. I'm using a prosoft card instead of SST and just loaded the sample logic into the CLX and it worked. The empty slot thing caught me out too! The GSD file for the Prosoft 3170-PDP Flex I/O adapter only gives you 9 slots, but you're right ... any unused slots have to be filled with the "EMPTY SLOT" module and the first slot always has to be the module status byte.

I've also got hold of some profibus PA instruments (Endress & Hauser)which I've got working with the CLX through a Siemens DP/PA coupler. This caused me a bit of head scratching until I found out that the process variable (4 byte floating point) has all the bytes reversed! Then it was a simple matter of using a SWPB instruction in the CLX to sort out the byte order.