Applies To:
  • CitectSCADA 3.xx, 4.xx, 5.00

The Citect drivers used to communicate to Allen-Bradley PLC2 Series (including the ABTCP2, ABEI2, ABKT2, KE2, KT2 drivers) seem return incorrect BCD values. Why ??

When a BCD is defined, bits 0 to 17 (octal) of the word are converted to produce a value 0 to 9999. For Allen-Bradley PLC2 series PLCs, bits 14 to 17 (octal) are used by the PLC to store status information. The solution is for the drivers to ignore the bits 14 to 17 (octal) when accessing PLC-2 data as BCD or LongBCD.

CIT has confirmed this to be a problem in Citect for Windows versions up to and including Version 4.20. This problem has been fixed in version 5.00.