Multi-timestamp factor (MTSF)

The MTSF specifies how many events (signal edges) are transferred from the buffer to the controller per PLC cycle.

The buffer has a capacity of 32 events; the MTSF can be 1, 2, 5, or 10 events.

Calculation of the MTSF

To choose the right MTSF, estimate the frequency of events expected at the input.

In order to avoid the transfer of excessive quantities of process data, the following configuration recommendations apply:

Synchronous operation:
Asynchronous operation:

(n_Events is the expected maximum number of input events per PLC cycle)

In asynchronous mode, only half as many events can be retrieved per time as in synchronous mode due to the handshake.

Setting the MTSF

Set the MTSF by selecting the corresponding Predefined PDO Assignment. See chapter Configuring the process image.

Example

With a cycle time of 1 ms, a maximum of 4 events/ms per channel are expected. All 8 channels of the box are to be used.

Synchronous transfer: MTSF ≥ 5

Select the Predefined PDO Assignment "Multi-Timestamping 8 Ch. 5x".
If more than five events occur in a cycle, these are temporarily stored in the channel buffer. The buffer can then be emptied by the controller in the subsequent cycles.

Asynchronous transfer: MTSF ≥ 9

Select the Predefined PDO Assignment "Multi-Timespamping 8 Ch. 10x".

Process data

For example, the process data of an input channel for MTSF = 1, 5 and 10 are as follows:

A bit in the inputs array (right-aligned) and a timestamp are available for each event.
These process data are placeholders that will receive events, if there are any to transmit.

If fewer channels are required, Predefined PDO Assignments is also available for 4, 2 or 1 channel, each with an MTSF of 1x, 2x, 5x and 10x.

If fewer events arrive at the input than defined by the MTSF, the remaining PDOs are set to 0, in order to highlight this.

Example: For "No of input events" = 3 and MTSF = 5, this means that the first 3 events are delivered in the timestamps "Input event time 1...3"; the timestamps "Input event time 4...5" have the value 0.