L_SMC_TouchProbe: Triggering with a Rising or Falling Edge

Description of the behavior:

The L_SMC_TouchProbe function block from the L_SM3_DriveUtil library correctly evaluates the first edge, regardless of whether it is positive or negative. After the first edge is detected, only edges of that type are subsequently passed through. Thus, only positive or only negative edges are detected.

Under what conditions does this behavior occur?

The behavior described above occurs when the TouchProbe evaluation is configured via the TriggerInput as follows:

TouchProbeMode = 2 (continuous measurement)

and

TouchProbeEdge = 3 (triggering with a positive or negative edge (logic in the function block))

Affected products:
PLC Designer version 3.0 and later

L_SM3_DriveUtil library, version 3.0 or later

Short-term measures:

Configure the TouchProbe evaluation to single measurement (TouchProbeMode = 1) and, after a detected edge, restart the TouchProbe evaluation using the xExecute input of the L_SMC_TouchProbe function block.

Assessment/Recommendations:
The L_SMC_TouchProbe function block can only detect one type of edge if the TouchProbe evaluation is configured for "continuous measurement" and the trigger is set to "positive or negative edge."

Note: No change is planned for this

[Automatic Translation]

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