Dear all,

In my case we have two number of PLCs. One is CPU 313C and other is CPU 226 CN with EM 277 card. Both PLCs are communicated through wireless antenna. The antenna which we are use that are on RS485 base.. But problem is that antenna are faulty. We want to replace antenna with ethernet antenna. So we required MPI to Ethernet converter so we add ethernet antenna. Please tell me if we add any mpi to ethernet converter and added ethernet antenna with master/client. This work or not?? Without changing in the program. 

Duris_I

Hello,

from your description of previous situation, it looks to me that general converter can be used, question is what Wireless system you have (no info from your side). In this case look maybe to Moxa converters but really hard to predict if this is correct solution, you need do tests. Of course I expect same adapter on end side. One attention is, you need look at speed of converter you want use, it need support your speed set on MPI network.

 The following wireless system we have used. Without access to PLC how to know that what speed set to MPI port on both side. 

Duris_I

Hello,

...

Without access to PLC how to know that what speed set to MPI port on both side.

 sry, you ask me? You need connect to PLC to verify or if you're sure about your Step7 prj is actual, look to your Step7 prj.

 Brother my project is password protected. And i have not password.. Antenna is Only RS232/485 option.. Its mean it have RS485 Protocol used in both PLCs. 

Hello jabbi_king;

The CP 341 provides serial, point-to-point connections over variou physical supports, Rs 232, TTY (curent loop) or RS 422/485. But that does not equate to a supported protocol. 

Sorry if you heard this from me before, but compare this to a telephone conversation. If I can dial your number and connect to you, it means we share the same physical support layer, wired or wireless.  But if you speak English and I only speak French, our protocols are different and our conversation will be pointless, we will not be able to exchange information. So in your investigation you must insure not only that both partners share a RS 485 layer, but that the same protocol and corresponding protocol parameters are setup so both participants can undertand each other.

The screenshot below shows the integrated protocols that can be used on a CP 341 RS 422/485 module. For a RS 485 setup, only ASCII protocol is avaliable (as integrated prtocol supported by RS 485). Now have  a look at this document showing the different parameters that must be set for ASCII comms:

https://support.industry.siemens.com/cs/ww/en/view/1117397/30259101835

Most important to you (as per your last comment) is the character delay time, related to the data speed setup in the driver. You could try all shown speed values in your system, and find the setup speed in your configurtion, maybe. That is if it is an ASCII protocol setup...

The CP 341 also allows a Modbus RTU loadable driver to be instaled and configured (after purchase), so the information given for the ASCII confguration would not be useful The way to ensure yourself about the presence of this Modbus driver is to verify is the CP 341 has a dongle installed on the back (the dongle enables Modbus RTU functions on the CP 341): remove the CP 341 from the S7-300 rack, and examine the back of te module; if you find a back plastic rectang;le inserted there, as shown in the following link, then your module is probably using Modbus RTU...

https://programmersought.com/article/42043751258/

Hope this helps,

Daniel Chartier

Dear its mean on the other side it used EM277. same like CP341?

EM277 order no. 6ES7277-0AA22-0XA0 

Duris_I

Hello,

then worse for you. It can be set without prj change I think. You can simply try check diagnostic of one of PLCs connected to MPI port, set on PG/PC interface MPI with specific speed. If you have set correct speed, you can see diagnostic of CPU, simple. I don't expect then different speed on other side. You can maybe set also MPI.Auto and do diagnostic from PG/PC interface which can show speed set on bus.

 If i connect laptop with A2 adapter over MPI port of CPU313C. And connect successfully. It means same speed set for CP341 port. Or i try to connect laptop at CP341.