Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 1.20, 2.00, 2.01
Summary:
With the KF Protocol, writing to several bits at the same time in the same word was not reliable.

The AB DH-485 Command Set for the SLC500 series provides no method of writing to individual bits. To provide this functionality, the KF driver reads a word from the PLC, modifies a single bit as required, and then writes it back. The driver has bug where writing to bits in the same word is not reliable.  

Solution:
To work around this problem, put the CITECT.INI setting MaxPending=1 under the [KF] section. The problem has been fixed and will be released in the next version after version 1.20 and 2.01. If you require this fix now, contact Citect Support. 
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