Applies To:
  • CitectSCADA 5.xx
Summary:
The following Citect protocol types have a maximum request size by default of 1888 bits:

ABTCP2, ABTCP250, ABTCP3, ABTCP5, ABTCP500

This is the maximum allowable value which will suit all the low level drivers normally used (SSTAB, CIKT, and TCP/IP). However the CIKT low level driver is capable of requesting up to 1920 bits. In some circumstances this might be desirable (e.g. when upgrading a Citect project from an earlier Citect version which used arrays of 120 words).

 

Solution:
To permit a larger request size when required, version 2.20 of the ABTCP driver has added the Citect.ini parameter MaxBits as described below:

MaxBits
Range: 0-2048
Default: 1888

The parameter is used as follows:

[ABTCP]
MaxBits =1920

MaxBits should be a multiple of 8. If this value is modified from the default then the protdir.dbf file in the Citect bin directory must be manually edited so that for the chosen protocol, the MAX_LENGTH field is changed to match. For example if MaxBits is set to 1920 bits for the ABTCP5 protocol then protdir.dbf should be modified as follows:

e.g.

ABTCP5 AB5 944 1920 0x37f

 
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