adccommunitymod (AutomationDirect) asked a question.
C-More Micro with Modbus RTU
Created Date: April 11,2008
Created By: EricMC
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I want to develop a small app before purchasing a screen. The comms to a PLC are through the Modbus Protocol. I set the PLC protocol to Modbus RTU. How do I assign the tags on the screen to memory locations on the PLC?
Created Date: April 11,2008
Created by: bcarlton
You will have to refer to the particular PLC documentation. If the internal references for the PLC are already in MODBUS format then it is easy. Otherwise you will have to refer to the PLC documentation for correspondence between MODBUS addresses and the internal addresses for the PLC.
Created Date: April 14,2008
Created by: OpZed
If you are accessing a Koyo PLC their is a spreadsheet on the tech website. http://support.automationdirect.com/docs/modbus_conversion.xls
But for other PLCs you'd have to research to see how they map the modbus addresses into their memory space.
Created Date: April 14,2008
Created by: EricMC
Thanks for the response.
I'm using a Twido PLC from Telemecanique.
If I'm reading or writing to/from a coil (ex: %M12) I would have Memory Type "0 " under PLC Address in Tag Name Database, and for reading and writing a word (ex: %MW6) I would use "4 " for the Memory Type?
Created Date: April 11,2008
Created by: EricMC
I want to develop a small app before purchasing a screen.
The comms to a PLC are through the Modbus Protocol. I set the PLC protocol to Modbus RTU. How do I assign the tags on the screen to memory locations on the PLC?