PLC Synchronization (PC-Handshake):

Whenever the PLC scans the encoder input, it must see stable data.  In order to ensure this, the PLC gives a data transfer command and a predetermined time later the PLC synch circuit stabilizes the data for the PLC to read.  This time is adjustable on some AVG Automation units (2 µs to 30 ms), where as it is fixed on others (50 µs, 100 µs, etc.).  The variable time feature, when available, can be used to provide the most fresh data to the PLC.

For example, the time interval between the data transfer and read commands might be 12 ms and say the time delay is set at 5 ms.  After 5 ms of the data transfer command the stable data is available to the input modules of the PLC and when the PLC commands the data to be read 12 ms later, it is stable and valid.