Incorrect data is sometimes logged when a tag from a Tecomat PLC is used to control data logging

By default, communication with a Tecomat PLC is realized at the level of tags. Communication packets are formed dynamically as currently required by the monitoring and control system. The defined communication zones are only used to specify the time interval used for reading the values of individual tags. For this reason, it is very likely that a new value of the control tag can occasionally be read while the tag values being stored have not yet been read. However, because the control tag determines the moment data is logged, data with an older time stamp is randomly logged to the database.

To make sure that the new value of the control tag and the values of the other tags are read at the same time (the tags must be located in the same communication zone), it is necessary that Teco Communication Driver's Communicate only via zones property be activated. You can find the property on the Communication page in the Communication Driver Manager. In this case, communication between the PC and the PLC is realized via communication packets exactly according to the definition of communication zones in the Device Manager.

This type of communication was first available in version 2.7.0 of Teco Communication Driver.

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