Check PLC connection

I would use:

bOnline = ((StrToInt(IODeviceInfo(sPLC,3)) BITAND 3) <> 0);    // populate sPLC with a valid I/O device name or number

This example works with redundant I/O devices as well, and will also catch states where the PLC is not fully on-line like 'Starting', 'Stopping', 'Disabled'.

You could also check for good quality of a known variable:

bOnline = QualityIsGood(PLCTag.Q);    // substitute PLCTag with a valid tag name

Regards,
Patrick

I would use:

bOnline = ((StrToInt(IODeviceInfo(sPLC,3)) BITAND 3) <> 0);    // populate sPLC with a valid I/O device name or number

This example works with redundant I/O devices as well, and will also catch states where the PLC is not fully on-line like 'Starting', 'Stopping', 'Disabled'.

You could also check for good quality of a known variable:

bOnline = QualityIsGood(PLCTag.Q);    // substitute PLCTag with a valid tag name

Regards,
Patrick