ModBus with Step-7

babree_a · Apr 30, 2009

Hello everybody,
I am using Siemens PLC 315 2 PN/DP and Modbus Library from IT4Busniess.
I have a motor simulator which have to send data to PLC which will be processed in PLC and after that Data will be sent to Operator Panel. Operator panel and Simulator both are made in LabView.
Anybody have idea to go forward?

Regards
Ali

JohnW · Apr 30, 2009

Do you mean using Modbus on RS485 or Modbus/TCP on ethernet?

babree_a · Apr 30, 2009

Modbus/TCP
This is first time i am programming PLC as my Bachelor Project in Automation.
I need some help that how i can recieve and send data from other computers to PLC and Process it.

JohnW · Apr 30, 2009

I am noy going to do your bachelors for you but the first thing is to read the documentation that came with the modbus library.

However to help you on your way.... you have to configure the SFB for modbus TCP comms and create some data blocks that convert the data to and from Modbus. Give it a go and get back when you hit any problems.

babree_a · May 6, 2009

hi again

Hello...we have got connection between PLC and The PC with labview...but now the problem is that we cannot get the data sent bye labview...can anybody help me...

JohnW · May 6, 2009

Have you set up the data block to read from Modbus?

babree_a · May 6, 2009

modbus

Yes i have done everything i could according to the manual.
there are DBs with modbus parameters for every connection,i made DBs to retreive data . when i download program to plc and run it i get 1 in the value of connection_established but dont get data in my DBs.

ModBus with Step-7

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