Applies To:
  • CitectSCADA x.x
Summary:
I can communicate with one Melsec PLC but I wish to Multi-drop Melsec PLCs using RS 422 or RS 485 multilink. I have set the communication switches according to the switch table, but it doesn't seem to work.  

Solution:
Your switch settings on the A1S module may be wrong (see Q1907). For multidropping:
  • Switch 2 Must be On (labelled ON for computer link and OFF for Multidrop-link? )
  • Switch 12 Must be On (to enable sum check)

All other switches according to communication parameters.

 
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