Hi 

i am working on  S7-1217 to VFD modbus communication.

how can i configure CM1242-5 for MODBUS communication?

is there any way to communicate with VFD using S7-1217 CM1242-5 modlue?

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Split from CM1242-5 Profibus Communication.

Hello Engr_Waqar;

Here is a description of the CM 1242-5, from Product Support:

6GK7242-5DX30-0XE0

COMMUNICATION MODULE CM 1242-5

COMMUNICATION MODULE CM 1242-5; FOR CONNECTION OF SIMATIC S7-1200 TO PROFIBUS AS DP SLAVE MODULE

You therefore cannot use this module to communicate over Modbus RTU, either master or slave.

Have a look at the following FAQ, it shows how to use a S7-1200 on Modbus RTU, and the required modules to do these serial connections:

How do you establish a MODBUS-RTU communication with STEP 7 (TIA Portal) for the SIMATIC S7-1200?

And here is a description of one of the recommended modules for modbus RTU connections, from the FAQ above:

6ES7241-1CH32-0XB0

COMMUNICATION MODULE CM 1241 RS 422/485 

COMMUNICATION MODULE CM 1241 RS 422/485; Sub-D 9 pin (Female) supports Message-based  Freeport.

Now that we have determined the hardware you would require for Modbus RTU exchanges to your VFD, do you know the Modbus mapping of your drive, and the Modbus Functions you must use to access the registers you want to read/write? If not, please describe the VFD (make and model) and if possible provide a communication manual of that VFD for Modbus RTU (a link will be perfect).

Hope this helps,

Daniel Chartier

Hi Daniel 

thanks for your contribution. i have no idea about VFD Address Mapping, VFD is Chinese made from SIAKO DIGITIZATION FORERUNNER.

Communications parameter pages missing from user manual.

checked on web but that manual not available on web.

model:SKIV100A1D5G-2

warmly appreciated  any guidance.

Hello Eng_Saqar;

Try with a manufacturer name SAKO.

I have located this chinese website, maybe you should contact them for details of their Modubs RTU comms, especially their Modbus mapping for your model of VFD.

http://sakopowersupply.manufacturer.globalsources.com/si/6008840272473/pdtl/Frequency-inverter/1052049818/Variable-Frequency.htm#

The site offers a chat option, it is worth a try.

You can also try to ask the vendor who provided the drive in your project.

Hope this helps,

Daniel Chartier