ModBMS will not allow an OPC Client to write OPC DA values to Sigma.

[Product_Support]

Issue

ModBMS will not allow an OPC Client to write OPC DA values to Sigma. But, reading the ModBMS/Sigma values does work.

Environment

Sigma 4.04 and below

ModBMS

OPC Client

Cause

ModBMS uses the DDE functions to read/write data to the Sigma server.  A Sigma release 4.04 and below the write function was not supported and was fixed in Sigma release 4.05 onwards.

Resolution

Upgrade to Sigma 4.05 (onwards) where the DDE write function has been fixed.