Applies To:
  • CitectSCADA 5.4x, 5.5x, 6.xx
  • CitectHMI 5.4x, 5.5x, 6.xx


I am losing communications intermittently between CitectSCADA and Honeywell PHD collectors.

CTAPI Errors 299 and 183 are showing in the PHD Event log. The system is under heavy load so I cannot run with CTAPI logging constantly turned on to trap CTAPI errors. Apart from the heavy loading, what could be causing these errors and communication failures.



Error 183 means file already exists.
Error 299 means that o nly part of a ReadProcessMemory or WriteProcessMemory request was completed.

Network problems may be ameliorated by adjusting the timeout value as follows:

SocketSendTimeout=5000 (increase further only if necessary)

Also add the following registry key:



Set it's original value to FC00 (hex), and increase this value until the problem no longer occurs. A reboot is required for the change to take affect.