S7 300 Modbus slave setup & test

danw said:

Does that CP 341 have Modbus RTU drivers? Apparently protocol drivers are loaded into Siemens comm modules, according to chit chat on the Siemens services forum site:


[*]The dongle that comes with the driver must be plugged in the back of the serial CP.


More information on loadable drivers for the serial CPs is available in the following manuals:

• "Loadable Drivers for PtP CPs; MODBUS Protocol RTU Format
  S7 is Slave" in Entry ID: 1218007.
• "Loadable Drivers for PtP CPs; MODBUS Protocol RTU Format
  S7 is Master" in Entry ID: 1220184.

Downloads

• Loadable driver "Modbus Master (RTU)" V3.1 SP4 can be downloaded in Entry ID: 27774018.
• Loadable driver "Modbus Slave (RTU)" V3.1 SP5 can be downloaded in Entry ID: 27774276.

Dan

Click to expand...

This was the root of all my issues. However when I read this post, I thought these drivers were included in the CD that came with the CP341 module.

Thsi is not so.

I also thought the dongle was only needed for the Master.

This is not so.

This page is where you find the new drivers for using the CP341 for modbus slave and master :

http://support.automation.siemens.c...r=true&siteid=csius&query2=&modelled=&lang=en

The dongle is required for master or slave.

Now I wonder why the 313slave.exe did not work but the 316slave.exe does?

My main confusion was that the choices on the parameter screen to choose modbus master or modbus slave simpley were not there.

When Bernie mentioned just doing the setup in the slave it set up enough conflict in my mind, that I began to question my whole aproach.

The areas of data to be shared are defined in the parameter screen , but only after you select modbus master or modbus slave and then select the "protocal" button to access the setup.

I looked all over and could not find it.

The slave address is also selectable in the same area with the data setup.

So it looks like the master does in fact do all the work. But the slave has to be preped for the request.

I accept that fully half of this was missunderstanding on my part.

I will go back and re-read the docs now and see where I got off track.

Good information here for the next guy though with plenty of links and reference material.

Thanks to everyone who contributed.

Have all the parts and software and the 5 documents

The effort continues.

I have the dongle installed, the drivers loaded, the parameters set and checked and rechecked. The slave address is set to "1" , the module ladder address is set to "256".

I have a sample program loaded from the CD included with the dongle.
zXX21_05_PtP_Com_MODSL

I used the "Modbus slave 300" example. seemed to be appropriate.

The preveious examples used FB7 and FB8 , this one uses FB80 which I read calls FB7 and FB8 internally.

When I use one of several Modbus testers , I get a "time out" error.

When I look in the DB for FB80, I find the error is W#16#00gc and the error info is W#16#1E0F

Sometimes the error is just 2 with no error info.

Siemens doesn't appear to provide any way to test this setup so I have no idea if it is even close to working.

5c hex is 92 dec. the error code for 92 is :

92 CPx41 FB 7->STATUS Error when executing a
RECEIVE/FETCH call with FB7
(RCV_RK)
Analyze FB7-STATUS

I'm not even using FB7 the documentation says FB80 handles all this.

not sure where to find the code for error info.

I just don't believe this can possibly be this difficult.

I have over 550 pages of documentation just for setting up S7 with Modbus RTU. After reading and searching for 20 hours, I am not convinced that the answer is in any of this documentation.

Make some screen shots of the 341 "parameter" section in the hardware config. and post them here.

One thing I noticed is in the hardware config, where the CP341 is added to the rail. The available choices are :

6ES7 341-1AH00-0AE0
6ES7 341-1AH01-0AE0
I have a:
6ES7 341-1AH02-0AE0 see jpg 13 & 14.

continued screen capture post

continued screen capture post not a duplicate

JRW said:

Make some screen shots of the 341 "parameter" section in the hardware config. and post them here.

Click to expand...

There they are

PLC comunication with CP341

Hi, I´m working with S7-300 SIEMENS and CP341 for modbus communication. I connect my RS232 from my PC to the CP341 RS485 port DB15 with the adapter 232/485 Siemens and leds Tx and Rx doesn´t flash...
Wich is the problem??
Thanks a lot
Martin

The modbus with S7 is not a simple issue.

I am covered up right now, but if you go to the Siemens website and fill out a service request asking for help with Modbus they will answer your queestions.

Richard Higginbotham is the guy you will probably get. He is very responsive and makes an effort to solve your issues. Very prompt and proffesional.

It will still take some time to work through all the variables though. I spent 3 weeks on just the modbus part of my project. Now I could do it all in 1 to 2 hours.

The help files and books fall short here.

The difficult thing for me was knowing what question to ask.

"It doesn't work." is a bad place to start.

Good luck.

Dear all

How can i adjoin between S7 & S5
i have a machine part of this machine worked by S5 and
Another part worked by S7. there is adjoin between the
two parts i can't this connection done.

better response from posting new question in forum