Hi experts and all friends.

I have read almost all modbus topics and I saw the benefit of topics that you have shared. Thanks.

I have a project that needs modbus rtu with s7-1200 OLC. I have done with PLC. It is slave and 

I got another PLC for master and I have tested with master PLC my slave PLC-s7-1200 cm1241 is 

working without problem.

My problem is that PC software can't comminicate with my PLC. I don't know where I do mistake.

I have tried many softwares. One of them is Radzio.(http://en.radzio.dxp.pl/modbus-master-

simulator/) but I don't know what my mistake is.

What I have done is below;

PC side

On PC side 5611 comminication card is cabled as profibus cable.

Radzio software (I have added a picture.)

PLC side

S7-1200-Slave (211-1AE40) (I have tested with other PLC which master)

Both side I am sure

Bitrare 9600 kb

Parity none

stop bit 1

Please I need to learn how to use PC as master because I can't find any PLC for master to test

when I go to service for start-up the project.

up the project.

I also have attached a video. (https://youtu.be/Wmwo85S-2uM)

Hello,

Plz try with Modview or modscan as Modbus Simulator software. I always test with this software and works fine without any issue. As Modview you can define as Modbus Master or slave as per your requirement.

Use serial converter as RS485 to USB to check communication between PLC and PC.

Just change the extension of ModBusView.txt to ModBusView.exe.

Hello Yusuf,

you can't use that CP5611 for this communication, it's suitable for MPI or Profibus network. Also exact info about CM1241 type is missing, is RS-232 or RS-485/422? Via this information you can select simple USB to (RS-232 or RS-485 due your CM1241) converter for PC and then you can make communication tests. You can buy that converters on web, they are very cheap, about 10 dollars. Be carefully in future select RS-232 or RS-485 interfaces, they working with different principles. Give us info.

Duris_I

I am using RS-485/422 two wire, I tested with another PLC on profibus cable

Hello,

ok, in this case you need USB to RS-485 converter or if you have some HW serial port (in most cases RS-232) you can use some RS-232 to RS-485 cable/converter. Pls think, everytime you need convert signals to your existing HW, but with that CP5611 isn't possible although it use RS-485 interface.

Yusuf,

look to your Picture to PC side interface, there is COM1 selected. Look to your PC HW Manager and check existing serial COM port. This is what you need to do and use for that. But also if it will be RS-232 on PC side, you need convert that signals to RS-485 because PLC module use it, clear now? That CP5611 can't simply act as simple communication converter, it has other 'Siemens' capability.

If I can say, in my opinion problem isn't with your SW used, problem is that you want use CP5611 for this communication, simply you can't. You must have other simple standard converter/adapter.

DJ_1

I have tried to use your software but still same problem "timeout":-(

Duris I am using the converter cable (http://www.s-link.com.tr/urunler/s-link-sl-32t-usb-to-rs232-cevirici-vaiec/)

Is it correct cable that I am using?

Yusuf,

this is USB to RS-232 converter not RS-485. Your PLC use (as you've posted info) RS-485 CM module, so you need convert also that RS-232 to RS-485. With only this adapter you can't work my friend, this info I've posted to you before.