Modbu TCP communication between EAE app and a third party PLC

[ibrahim.rebouh]

Hello everyone,

I’m working on a project where a Siemens S7-1200 PLC writes data via Modbus TCP to the holding registers of my PLC.
I would like to use EcoStruxure Automation Expert (EAE) for this application and install an M251 dPAC so the S7-1200 can write data to it.

Could anyone provide documentation or guidance on how to set this up on the EAE side (which function blocks to use, configuration steps, examples, etc.)?

Thank you in advance!

[theo.bagieu]

Hi @ibrahim.rebouh,

I assume in your use case that the M251d will be the modbus TCP Server (slave).
You need to use the library 'Standard.IoModbusSalve' 

Thanks to that library you will be able to setup a ModbusTCP server in your device HardwareConfiguration.
This is the default structure to define : 

Then, under MODBUSGENBC, you can add the registers or coils you would like to expose into the server.

The last step is to configure the properties : In MODBUS node properties, set up the IP address to the same ip than your M251d. You can edit some other properties like port etc...
Also, if required, in MODBUSGENBC, you can change the station id along with some other parameters.

Finally, for each added registers in the configuration, you can change the register type (Holding Register/Input Register, the addresses of the registers etc...)
You can find more information about this step in UserManual (UserManual > Ecostruxure Automation Expert - Buildtime Network Communications > Modbus > Manual Development)

Edit: Then you can create symlink in your application, and map them to the exposed registers in you hardware configuration.

Hope this helps

[ibrahim.rebouh]

Hi @theo.bagieu,

Thank you for the reply you have been a great help, i'll test it out and see.