Applies To:
  • CitectSCADA 5.20, 5.21 Service Pack B
Summary:
How do I set up my Modem in Windows specifically for Citect Dial up/Dial back. 

Solution:
A manufacturer provided '.inf' file when installing a particular modem may store an init string under the following registry key;

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}

Such an init string may set the modem for error correction, enable compression, handshaking, or other features which are OK for applications like "RAS" or internet access, but not suitable for communication to Citect dial up/dial back I/O devices (PLCs).

Therefore it is best to not use RAS or other TAPI applications on the Citect I/O server, for Citect V5.20 through to V5.21. It is anticipated that incompatibilities between Citect and other telephony applications will be resolved in V5.3x.

Always install modems for Citect dial up/ dial back in the following manner;

Allow the O/S to detect the modem (uncheck the " Don't detect my modem . . . " box). This will force the Windows modem driver to use Citect compatible init strings. That is, do not load any ' .inf' file and ensure that we always install one of the "standard modem types" (a 300bps ~28800bps).  This is the correct installation method for Citect V5.x and may resolve dial up/dial back problems.

 
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