Applies To:
  • CitectSCADA 1.00 1.01 1.10 1.11 1.20 2.00 2.01 3.x 4.x

The Modbus plus MBPLUS protocol has a limitation of 8 PLC per interface card. 

The only work around to this limitation is to use more Modbus Plus cards. You will need one card per 8 PLCs.

The latest version of the Modbus Plus driver has worked around this limitation. This driver is shipped with version 3.21 and later. Upgrade to version 3.21 or later if you want to communicate to more than 8 Modicon PLCs over Modbus Plus.