Applies To:
  • CitectSCADA 5.xx, 6.xx, 7.xx 
  • VijeoCitect 5.xx, 6.xx, 7.xx

Summary:
When using Modbus20/Modnet20 or Modbus30/Modnet30, the protocols allow you to use the %M and %MW of Unity addressing. However, it does not allow you to use the %I and %Q addressing of the input and output register, respectively.

How can we configure the variable tag defined in Citect to refer to those registers?

Solution:
Modbus flat addressing is not supported by the Unity topological addressing. Therefore, in order to incorporate those registers in Citect, we will need to map the I/O to the internal storage in the PLC.

Therefore, the registers which have the addressing of %Ix.x.x.x or %Qx.x.x.x need to be mapped to %Mxxxx and/or %MWxxxx.

Then, we can use either %M or %MW addressing or the modbus equivalent format.

Keywords:
 modbus, modnet, unity, address, conversion, input register, output register, %I, %Q

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