Applies To:
  • CitectSCADA 5.xx, 6.xx
  • CitectHMI 5.xx, 6.xx
Summary:
During a General Update poll request, the driver seems to get into a bad state. Shortly after #COM is displayed on the display page.

A driver trace shows the following sequence of events:
1) Driver init
2) Init unit brings PLC online. (Transmit: 01 02 01 00 07 00 7B DD)
3) Driver requests a general update - Op Code 0. (Transmit: 01 02 01 00 00 02
00 02 C3 DC)
4) Driver receives a response. (note 20 is the trailing character EOM).
5) Shortly after, the driver times out:
Thu Apr 27 13:42:49 2006 360:03:12.331 Error: Channel offline, cannot talk
READ 0015 PORT1_BOARD1 IODev AI1 3
Generic 000021 Driver 00000020 (0x00000014)

What is wrong, and how do I fix this problem?
 

Solution:
This problem is caused by a Driver parameter TINPollTime defaulting to 16 seconds. This type of data type was never implemented in the ROC driver, and enabling it causes the ROC driver to get into a bad state.
The solution is to disable this parameter:

[ROC]
TINPollTime=0

Citect has confirmed this to be a problem in ROC driver version 2.00.00.000 to 2.01.03.005. We are researching this problem and will post new information here as it becomes available.
 
Keywords:
General Update, TINPollTime, ROC, #COM 
 

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