Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 1.20, 2.00, 2.01

When an Omron PLC is powered up, the default operating mode is "RUN". When the PLC is in Run mode, some registers cannot be written to. 

To write to these registers the PLC must be in Monitor mode. There are some status registers that can be written to, writing a "1" to the appropriate register will change the mode. The registers are as follows.

S0 Program Mode.
S1 Debug Mode.
S2 Monitor mode.
S3 Run Mode.

These addresses should be configured as type DIGITAL in Citect. All these registers are not present in all PLC's, but the important one is S2 for Monitor mode (which should be in all PLC's).