Hello everybody. I have a problem a little bit similar to this one.

I am trying to establish a Profibus communication between Allen Bradley ControlLogix 5550 via a SST PB3 CLX module (master) and Siemens S7-300 CPU314C-2DP (slave). 

I've configured the SST module by giving it an address an defining the input and the output modules and also indicating the S7-300 's DP address. the LEDs' state let me think the configuration is ok  (COPN is displayed and COMM and OK leds are green while SYS led is amber). When i launch the automatic research, the SST configuration sowftware detects the node of the S7-300.

On the other side, i configured the Profibus network on SIMATIC Step 7 by giving the same DP adresses to the CPU314C-2DP and a station representing the SST Profibus module.

I've also configured the input and output modules in the DP port in HW Config. the modules have the same size as those created in the SST profibus module congifuration. 

Thus when i go online, the SYS del is lit RED and the CPU tells the offline configuration differs from the online configuration. I cant figure out what the problem is.

It's been a long time now since i've been stuck on this issue.

ANY KIND OF HELP WILL BE APPRECIATED  !!!

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Split from Profibus communication through Siemens DP/DP Coupler to Allen Bradley PLC SST Profibus Module.

Hello sekousagna;

You seem to have understood the basic principles of setting the CPU 314-2DP as a slave, and determining the data exchange areas that you will use to communicate with the DP-master.

The diagnostic messages you show from the S7 314-2DP indicate a mismatch of the configuration.

This can happen if the modules you have setup for data exchange are not reversed between the master and the slave.

For example, if you have configured 2 areas of data exchange  in the S& slave:

- 16 words IN

- 32 Bytes OUT

then in the master you should have:

-16 words OUT

- 32 bytes IN

Same sequence, same size of data, but reversed in/OUT.

Why don't you show us a screenshot comparing the data exchange areas between the slave and the master, it would help us see if that is the problem.

If you still have problems, you could study the following document. It demonstrates the configuration of a S7-300 DP-slave to a master (also a S7 PLC) programmed in a different project. This is quite close to what you are trying to do, ba S7 project for the slave, a ControlLogix project for the master.

How do you add a CPU as DP slave to the DP master system of a different CPU whereby the CPUs are configured in different STEP 7 projects?

Note that, like much of Siemens documentation, this FAQ is available in French, if it can help. Simply scroll down to the bottom of the document and select the French link you will find there, along with German, Chinese, Italian and Spanish versions.

Hope this helps,

Daniel Chartier

Thank you @dchartier for your valuable contribution. Yes i've studied a lot of documents and examples of this communication system and i understand the basics. I didn't forget to invert the inputs/outputs on the SST side and the S7-300 side that's why i dont understand what the problem is. I've attached screenshots of the modules configuration on both sides.

Thank you !

Hello sekousagna;

I have worked with SST modules a few years ago, and I do not remember that the first 3 modules of the Profibus configuration should be dummy modules.

Normally, if the slave uses modules 1 and 2, the master should match the same module distribution and numbers; the master should have modules 1 and 2 also (same data size but reversed).

See if you can remove the 3 first (dummy) modules of the SST master, see if it accepts the configuration, and if your error messages clear up.

By the by: 13 words is not a standard module size; you might want to change that to 16 words both on the master and the slave, even if you lose access to 3 words on each CPU.

Hope this helps,

Daniel Chartier

Hello dchartier,

The dummy modules on the SST Profibus side represent the S7300 Power and the CPU emplacements configuration. I tried not to integrate them but the configuration of the SST didn't work. But i'll try to eliminate them and see what happens. I'll also modify the in/out modules lenght to 16 Words. Maybe that could solve the problem.

Thank you !!

Seckou Sagna

Hello,

I tried to apply the advices you gave me but it didn't work. First, i changed the the modules' lenght to 16 Wo but the fault persisted. Then i supressed the dummy modules in the SST Profibus configuration but it created a bus fault on the S7-300 CPU. But i noted that in the SST configuration, the output module is at the emplacement 3 while the input module in the S7-300 is at the emplacement 4. In addition, the input module of the SST configuration is at the emplacement 4 while the output module of the S7-300 is at the emplacement 5. The problem is in the S7-300 the emplacements are distributed automatically to the modules i create, i can't control it. And if i try to match the emplacements distribution on both sides by creating a fourth dummy module (emplacement 3) and then creating the output and input modules ( emplacement 4 and 5), the configuration of the SST fails and the CPU lets a Bus Fault appear.

Thanks for investing your time and energy !

Seckou Sagna 

 Hello dchartier,

I've applied the suggestions you gave me with no result. I thought you may have other tips to help me with.

Seckou Sagna

dchartier

Hello sekousagna;

I have worked with SST modules a few years ago, and I do not remember that the first 3 modules of the Profibus configuration should be dummy modules.

Normally, if the slave uses modules 1 and 2, the master should match the same module distribution and numbers; the master should have modules 1 and 2 also (same data size but reversed).

See if you can remove the 3 first (dummy) modules of the SST master, see if it accepts the configuration, and if your error messages clear up.

By the by: 13 words is not a standard module size; you might want to change that to 16 words both on the master and the slave, even if you lose access to 3 words on each CPU.

Hope this helps,

Daniel Chartier

Hello seckousagn;

I just might have another solution...

A little bit of research (I should have started with that! type of search, instead of relying on failing memories...) made this Siemens Application Example available:

Comm. with Third-Party Contr. (Allen-Bradley) ID No.: 23809864

It examines the configuration of a SST PB3 CLX as Profibus master with a Siemens S7-315-2DP as a slave. It would have saved you a bit of time, it corresponds quite nicely with your project...

The screenshot below compares the 2 configurations. it seems that contrary to my recollection both the master and the slave must have 3 empty modules before the actual data exchange modules can be inserted in the configuration...

The copmplete document will of course be useful, as it explains the RLL (A-B for Ladder) code required for the SST master; this will also save you much time.

Hope this helps,

Daniel Chartier

Hello dchartier;

Thanks again for this tip. I'll explore this way maybe it will lead me to the solution ! Thanks Again !

 Hello dchartier,

I finally found a way to make it work. Actually the problem was the SST module didnt start up, it needed a ladder code that manipulates its internal registers to turn it on and to open the profibus gate. I found the ladder code in the SST-PB3-CLX getting started document. Now i am able to send data and receive data on both of the S7300 and the AB CLX controllers. But the problem i am facing is the modules vehicle datas in INT type and when i send REAL values, the SST inverts the Most significant byte and the Low Significant Byte so the value i read in real isn't the one i send, but actually the one i send that got his bytes switched. I tried to solve the problem by using a Bit shift instruction in a loop but it appeared to get complicated so i am asking if there isnt a better solution ?

Thanks !!

dchartier

Hello seckousagn;

I just might have another solution...

A little bit of research (I should have started with that! type of search, instead of relying on failing memories...) made this Siemens Application Example available:

Comm. with Third-Party Contr. (Allen-Bradley) ID No.: 23809864

It examines the configuration of a SST PB3 CLX as Profibus master with a Siemens S7-315-2DP as a slave. It would have saved you a bit of time, it corresponds quite nicely with your project...

The screenshot below compares the 2 configurations. it seems that contrary to my recollection both the master and the slave must have 3 empty modules before the actual data exchange modules can be inserted in the configuration...

The copmplete document will of course be useful, as it explains the RLL (A-B for Ladder) code required for the SST master; this will also save you much time.

Hope this helps,

Daniel Chartier