Hello;

The S7-300 and S7-400 PLCs use an integrated MPI port for programming and basic communications with Siemens automation equipment. MPI is based on the RS-485 electrical standard, but it is a dedicated protocol, and the integrated MPI port cannot be used to connect to a 3rd-party equipment for serial commnications.

For this you need a serial RS-485 communication processor, either a CP-340 or a CP 341 for the S7-300 CPUs, and you must program the serial data exchanges with the help of configuration software provided when you purchase the CP, or that you can download from this site (use the Search box at the right of this page to locate them).

The following link will show you the connections used by the CPs, and links at the bottom of the page will help you see the basics of communication with a CP 340/341.

How do you connect the RS485/RS422 interfaces of SIMATIC and SIPLUS modules for serial communication? (Examine figure 3)

https://support.industry.siemens.com/cs/ww/en/view/109736665

Hope this helps,

Daniel Chartier

dchartier

Hello;

The S7-300 and S7-400 PLCs use an integrated MPI port for programming and basic communications with Siemens automation equipment. MPI is based on the RS-485 electrical standard, but it is a dedicated protocol, and the integrated MPI port cannot be used to connect to a 3rd-party equipment for serial commnications.

For this you need a serial RS-485 communication processor, either a CP-340 or a CP 341 for the S7-300 CPUs, and you must program the serial data exchanges with the help of configuration software provided when you purchase the CP, or that you can download from this site (use the Search box at the right of this page to locate them).

The following link will show you the connections used by the CPs, and links at the bottom of the page will help you see the basics of communication with a CP 340/341.

How do you connect the RS485/RS422 interfaces of SIMATIC and SIPLUS modules for serial communication? (Examine figure 3)

https://support.industry.siemens.com/cs/ww/en/view/109736665

Hope this helps,

Daniel Chartier

hi thanks for reply but let me konw what is the rs-485's type? A?b?D?

AutoGen_912446

 

hi thanks for reply but let me konw what is the rs-485's type? A?b?D?

 

Hello;

I do not understand your question. What exactly are you asking?

Daniel Chartier

Hello bhargavp;

If your search was not conclusive, maybe the information in the attachment below can still be of help.

Hope this helps,

Daniel Chartier