S7-1200 CPU with a CM 1242-5 - How to set up the Input/Output communication to match the data addresses of the Comms Module?

Hi All - This is my first post on the Support system and I'm a completely new to DP-DP slave communication. 

I have a new S7-1200 CPU fitted with a CM 1242-5 comms module that I am trying to interface via profibus with my master system which is a CPU 417-4 programmed in Step 7.

l have added the CP-1242-5 module to the master HW profibus configuration in step 7 as a Profibus Slave however I'm unsure how to set up the Input/Output communication to match the data addresses of the Comms Module.

Do the Addresses of the Input / Output Byte and Word modules that need to be dragged into the CM1242-5 config need to match the slave addresses allocated on the s7-1200 side??

i.e - If a digital output from the S7-1200 is addressed as Q500.0 at the DP slave (CM 1242-5) - does it need to be addressed as I500.0 at the CM 1242-5 adddressing in the main project HW configuration?

I hope this makes enough sense for someone to assist? 

Thank you all for any help on this.

John Higg

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Split from Communicate S7-400 and S7-1200 using GET and PUT functions.

Hello John;

The address numbers do not have to match between the slave and mater configurations; the important issue (as you have noted already  ) is that the data size be the same in both configurations, per data exchange module and that inputs to the slave be connected to outputs from the master, and vice-versa.

However, since address selection is the choice of the programmer, it is often easier to use similar addressing in master and slave to make the naster-slave relationship more evident.

Hope this helps.

Daniel Chartier