Hey ,

Can someone explain me what's programming difference in realisation of the modbus rtu regarding these 2 CPUs.

I have worked with s7-1200 and with CM in your program you just need in a case of modbus master to use 2 functions. One function you use once in OB100 and another you are using cyclic in OB1

First function is Mb_comm_load(OB100)

Second function is mb_master_fb (OB1).

I dont need to take care of the modbus protocol rules with s7-1200 modbus rtu solution.

My question is how this going with ET200s side cuz friend of mine told me here we have to deal with construction of MODBUS message. IS that true?

So with Et200s CPU and 6ES7-138-4DF11-0AB0 there are function S_SEND and S_RECEIVE.

Should I take care for modbus message rules? COnstantly send requests with S_SEND to 6ES7-138-4DF11-0AB0 and constantly listen incoming bytes with S_RECEIVE from 6ES7-138-4DF11-0AB0.

Or basically all has been resolved on its easy way with those two functions same as it is case with s7-1200 and CM RTU 485 module

Hello,

I don't see reason to say that it must be done programatically. System is functional with very identical system like in CP341 Modbus programming, so defining init DB where is defined all required like Slave address, FC code and other needed data depended to request. Then you call Send block with your DB defined and receive via RECV to DB receive block. Don't understand what your colegue meaned. You can also find documentation about Modbus programming with ET200S DF11 CM here on forum somewhere and read all what will be important for you.

Update: eeeeeehm now I don't understand why you ask this question because in this your topic you mentioned that aal is working ok with ET200s:

MODBUS RTU - will it work on this way

Duris_I

Hello,

I don't see reason to say that it must be done programatically. System is functional with very identical system like in CP341 Modbus programming, so defining init DB where is defined all required like Slave address, FC code and other needed data depended to request. Then you call Send block with your DB defined and receive via RECV to DB receive block. Don't understand what your colegue meaned. You can also find documentation about Modbus programming with ET200S DF11 CM here on forum somewhere and read all what will be important for you.

Update: eeeeeehm now I don't understand why you ask this question because in this your topic you mentioned that aal is working ok with ET200s:

MODBUS RTU - will it work on this way

 It does works, but programs in our company are done by all of us. Since program for MODBUS RTU with ET200s as master has been done by someelse and that someelse told me that its way harder to configure program than in s7-1200 I posted this question.Yes his program works fine but I am trying to see what should be different than in s7-1200

This friday or monday will have  equipment here so i will tell bymyself, my goal is to test 

https://support.industry.siemens.com/tf/ww/en/posts/modbus-rtu-will-it-work-on-this-way/170132/?page=0&pageSize=10

Inside ET200s Serial interface  modules PDF

on the section 3.5,4 Function Codes Used by the Modbus Master it says The table below lists the function codes supported by the Modbus master driver.

Do I get this driver together with 6ES7-138-4DF11-0AB0  or it must be ordered separatelly or what?

Maybe this is what my colleague meant.

I have checked code on https://support.industry.siemens.com/cs/document/25358470/function-blocks-examples-and-user-manuals-of-the-serial-interface-et200s-1si?dti=0&lc=en-WW

and there is exaple with s7-300 and ET200s Interface module + 1SI module

Thats exactlly what I have asked whether its works on another post. So looks like its possible. 

I havent found anywhere on this example that I need to confgure bytes according to modbus rules.

Its already done by SIEMENS but I'm not sure is that case with modbus driver or without. Point is what is modbus driver? My 1SI module or??

Hello,

https://en.wikipedia.org/wiki/Device_driver