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 A and B channels are 1Vp-p cosine and sine waves that will produce an incremental count that shows up in the INCREMENTAL data box on the Data Display.
Since the A and B channels are cosine and sine waves, their amplitudes can be used similarly to a resolver to produce yet another angle that has not been show on the Data Display in the past. This angle is now displayed in a box called the Analog Phase Offset. This Analog Angle will go through 360 degrees a number of times in one revolution.
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 changed by using the electronic alignment 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 "OK" or "ERROR". We also include a clock face visual. Simply double click inside the ANALOG OFFSET STATUS window to see the relationship. The refAngle (serial position) is the first angle shown in the Analog Error box. The second angle is the analogAngle calculated from the cosine and sine voltages. The second angle is subtracted from the first angle to get the Analog Phase Error.
- To the right of the error number, "OK" will appear if the error is within tolerance (within 12 degrees of zero). If it is out of tolerance "ERR" will follow the error number in place of OK.
- Due to time lag in the serial data response, the encoder must be stationary for the error number to be meaningful. Please ignore the error number and ERR if the encoder is not stationary.
- Since it must be stationary, it is good to try a few different positions to verify that it always shows OK. Just be sure that it is stationary when you read it.
- If it consistently shows ERR, 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.
- If the Analog Offset Status says ERR no matter what, than this can indicate a problem with the incremental lines. Make sure to perform a Line Levels test to verify these signals are working correctly.
- It turns out that the drives that are used with Rexroth MSK motors actually check to make sure that the analog channel and the serial data are in this relationship within a tolerance. The tolerance seems to be fairly broad and the analog angle can be more that 90 degrees from zero when the serial count is passing through zero. But if the error is much more than that, the drive will produce a C0220 alarm or similar error. Make sure the status is OK for Rexroth MSK motors.
- Other brands of drives (like Allen Bradley and many others) do not error out on the Analog Offset Status.