Which products are affected?
ESP-SPAC-CAM1 – Software Package Cam V1.1 (cam library LenzeCamControl1.lib)
What happens?
The y-clock pulse length of the dnYEndPos_p is not correctly calculated for all clock pulses by function block L_CamData. The function block L_CamControl which usually follows uses this signal to calculate a profile position dnSetMainPos_p between 0 and the stop value of the feed profile yEnd. The value L_CamControl.dnSetMainPos_p is drifting.
When does the problem occur?
The problem occurs if the master position at function block input L_CamData.dnXPosIn_p exceeds the clock-pulse limit several times or jitters (e.g. in case of a relative master value selection via encoder emulation at X9) when feed profiles are used (L_CamData.bProfileRelative = TRUE). For the above-described behaviour, the y-clock-pulse length furthermore must have a non integer incremental value. The problem can also occur in template cam.
Possible diagnostics?
The problem can be reproduced if the master position at function block input L_CamData.dnXPosIn_p exceeds the clock-pulse limit several times or jitters (e.g. in case of relative master value selection via encoder emulation at X9) when feed profiles are used (L_CamData.bProfileRelative = TRUE). In this case, the profile position dnSetMainPos_p drifts at function block L_CamControl.
Short-term measures/recommendations?
Limitation of the direction of rotation of the master value to avoid repeated x-clock-pulse transitions. If the master value is selected via phase difference signals (e.g. digital frequency selection via X9) the function block L_CamLimitVelocity can be used to ensure that the master value does not rotate in ccw direction/jitter.
With jittering, absolute master values (x-positions) repeated clock-pulse transitions must be prevented, e.g. by stopping the master shaft at a position other than the clock-pulse transition.
Evaluation
The error is caused in an internal calculation of the function block L_CamData. It does not lead to a drift of the drive shaft itself, but to a faulty calculation of the current profile position. If the error occurs with feed profiles, the clock-pulse reference gets lost. Trouble-free profile mode operation and positioning is then no longer possible.
