L_SMC_TouchProbe: Triggering with positive or negative edge

What happens?
The FB L_SMC_TouchProbe from the L_SM3_DriveUtil library evaluates the first edge correctly, no matter whether the first edge is positive or negative. After the first edge has been detected, only edges of this type will be accepted. I.e. only the positive or the negative edges will be detected.

When does this behaviour occur?

The above-described behaviour occurs if the TouchProbe evaluation is configured as follows via the TriggerInput:

TouchProbeMode = 2 (continuous measurement)

and

TouchProbeEdge = 3 (triggering with positive or negative edge (logic in the FB)

Which products are concerned?
PLC Designer from V3.0

L_SM3_DriveUtil library from V3.0

Short-term measures:

Set the TouchProbe evaluation to single measurement (TouchProbeMode = 1) and restart the evaluation by means of the xExecute input of the FB L_SMC_TouchProbe after an edge has been detected.

Evaluation/recommendations:
If the TouchProbe evaluation is set to "Continuous measurement" and triggering on "positive or negative edge" the function block L_SMC_TouchProbe can only detect one edge type.

URL for linking this AKB article: https://www.lenze.com/en-de/go/akb/201400006/1/