Operation modes

The EP31xx supports three different operation modes:

Operation modes 1:

Fig. 3: Relationship of operation modes

The module switches between the Freerun (filter on) and Synchron modes by activating/deactivating the filter via the index. This takes place while the module is in OP mode. The changeover may result in longer sampling times and step changes in the process data until the filters have assumed a steady state.

DC mode can only be used when the filters are switched off. Likewise, it is not possible to switch the filters on in DC mode. The DC mode is parameterized via the DC tab in the TwinCAT System Manager.

Synchron mode

In synchronous operation process data are generated frame-triggered, so that a new value is available with each PLC cycle. Synchronous mode is used automatically with the EP31xx modules (filter off, no DC). The minimum cycle times are 80 µs (EL31x1/EL31x2), and 120 µs (EL31x4) for standard IPCs.

DC operation

In DC mode the analog sampling is triggered by DC-interrupt. As a result, the temporal jitter between two frames is no longer important and the sampling point is the same across the entire system.

The "input-based" mode shifts the sync-interrupt in such a way that the process data are ready for collection shortly before the current process data cycle.

If the frame jitter is too large, it is possible that data may be collected twice or there may be interruptions in the transmission. In that case the jitter is to be reduced through TwinCAT system measures or a slower cycle time is to be chosen.