how can i read/write data btwn 3100-3150 MCM and  cp 341

with simatic ?

Hello amr;

Both of the Prosoft and the S7 Modbus communication modules can be either master or slave. You have to decide at the start which one will be master, and which one will be slave; this will affect the way you configure and program each one in this project.

To make sure you understand the basics of Modbus communications, especially on 2 non-Modicon platforms, here is a very well designed presentation of the Modbus protocol, prepared by our friend smiffy. It is short and compact, and will clarify the basic terminology of the Modbus data exchanges:

https://support.industry.siemens.com/tf/WW/en/posts/modbus-general-description/66876?page=0&pageSize=10

Here are basic manuals for the Prosoft module and the CP 341, examine them with the Modbus General Description in mind, to recognize the terms and concepts used with Modbus exchanges. Section 7.9 of the Prosoft document shows the parameters to choose if you want to set the module as master or slave; section 5 of the Siemens manual describes programming of the module as master or slave, once you have selected the correct software package; you will find the part numbers for Modbus master and slave protocols in the manual below.

https://www.prosoft-technology.com/content/download/5277/37714/version/9/file/3100_3150_mcm_user_manual.pdf

https://cache.industry.siemens.com/dl/files/653/88867653/att_71909/v1/88867653_faq_en.pdf

Note that you must also take care of the physcal aspect of the communication setup: you must make sure that the supported physical layer of both modules is correcty selected and wired. The Prosoft module has 2 ports that can be configured to work with RS-232 or RS-485. The CP 341 comes in 3 distint designs, one for RS-232, one for RS-422/485, one for TTY (current loop); you must puchase the CP 341 model that will match the settings on the Prosoft module,

Come back to us when you have read up on the Modbus modules and communication principles, and have selected the correct modules and software versions. We can help you further your programming on the Siemens side.

You will have to tell us then what programming software you plan to use with your S7 CPU (Simatic Manager v5.x or TIA Portal v1x), which module will act as master, how much data you plan on exchanging between the Modbus partners and where these values are located in the respective CPU memory.

Hope this helps,

Daniel Chartier