SICK Stegmann Hiperface encoders produce a serial count for positioning that can be read in the serial Position Count section of the Data Display. The analog signals are 1Vp-p sine waves that will produce an incremental count that shows up in the INCREMENTAL data box on the Data Display.
New Hiperface encoders are set up so that the serial count and analog signals have a certain relationship. The serial position count will go through zero when the A (cosine) channel is at a max positive voltage and the B (sine channel) is going through zero ( B relative to B*). This is a 0 analog angle.
The Electronic Commutation procedure in use on the TI-5000JX changes the zero position of the encoder's serial count to allow electronic alignment of the encoder. While it can change the serial position, it has no effect on the analog angle, so the relationship found on new encoders may be altered by using the electronic alignment tool if the "Preserve Phase" box is unchecked.
In order to help the technician verify that an encoder has the required relationship, the Data Display shows the relationship with a simple "OK" or "ERROR". We also offer a more detailed view that includes a clock face visual and specifics on the various counts. Simply double click inside the ANALOG OFFSET STATUS window to access the detailed view. The refAngle (serial position count) is subtracted from the analogAngle (analog position count) to get the resulting Analog Phase Error (offset).
NOTES
- The ANALOG OFFSET STATUS field will show "OK" if the offset error is within tolerance of +/-2 counts from zero. If the offset error is greater than 2 counts it will show "ERROR".
- Due to time lag in the serial data response, the encoder must be stationary for the status to be meaningful.
- It is a good practice to try a few different positions around the encoder to verify that it always shows OK. Just be sure that it is stationary when you read it.
- If it consistently shows ERROR, this could have been caused by using the Electronic Alignment with the "Preserve Phase" unchecked. This problem can be corrected by electronically aligning it again with the Preserve Phase box checked. It could also indicate a problem with the incremental lines. Make sure to perform a Line Levels test to verify these signals are working correctly.
- The Rexroth MSK series motors use drives that check this offset relationship. Their tolerance seems to be fairly broad compared to ours, but the drive will produce a C0220 alarm or similar error if this offset is out of range. Make sure the status is OK when testing Rexroth MSK motors. Other brands of drives (like Allen Bradley, Control Techniques, and many others) do not produce alarms if the Analog Offset Status is in ERROR.
- We display 32 counts on the clockface because, with all Hiperface encoders, the number of serial position counts is always 32 times the number of analog periods. For example the SRS/SRM is 32,768 counts and 1024 periods, while the SKS/SKM is 4096 and 128. This means that, no matter what the encoder's count resolution, there will always be 32 serial counts per analog period.
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