11-13-2018, 03:10 PM
(This post was last modified: 11-17-2018, 02:17 PM by Eskimo2k.

*Edit Reason: Realized I made a typo on the Medium track frequency. It is really 32, not 8.*)
This dead horse has been beaten enough, but I got sucked back into it after a couple of years of (successfully) ignoring it.

The OLD iGaging Absolute scales use a 52 bit data packet transmitted every 0.1 seconds. That's a 10Hz refresh rate, so they are pathetically slow for what we want. But there are people out there that still have them. Anyway, the data packet contains a 25 bit data segment that encodes the actual position. That 25 bit segment has 3 data words in it, the Coarse track, the Medium track, and the Fine track. The bit sizes are 8 bit, 8 bit, and 9 bit, respectively.

Through observation and a little math, it's been found the total length of the Coarse track (or period) is 1310.72mm with a frequency of 1, the Medium track has a frequency of 32, and the Fine track has a frequency of 256. The phase offsets are not yet known, but are being worked on. (If you don't feel like doing the math, those numbers give a resolution of 0.01mm, which is what iGaging claims).

Anyway, I'm not all that good with figuring out how to do the phase angle math for the 3 phase angles, and I'd appreciate any help anyone can offer!

FYI, I know this will never be incorporated into the controller firmware. These scales are WAY too slow in their response time and do not seem to be widespread. Custom firmware can be written (I probably will write it for a friend who has these scales) and it'd great to be able to support as many scales as possible!

The OLD iGaging Absolute scales use a 52 bit data packet transmitted every 0.1 seconds. That's a 10Hz refresh rate, so they are pathetically slow for what we want. But there are people out there that still have them. Anyway, the data packet contains a 25 bit data segment that encodes the actual position. That 25 bit segment has 3 data words in it, the Coarse track, the Medium track, and the Fine track. The bit sizes are 8 bit, 8 bit, and 9 bit, respectively.

Through observation and a little math, it's been found the total length of the Coarse track (or period) is 1310.72mm with a frequency of 1, the Medium track has a frequency of 32, and the Fine track has a frequency of 256. The phase offsets are not yet known, but are being worked on. (If you don't feel like doing the math, those numbers give a resolution of 0.01mm, which is what iGaging claims).

Anyway, I'm not all that good with figuring out how to do the phase angle math for the 3 phase angles, and I'd appreciate any help anyone can offer!

FYI, I know this will never be incorporated into the controller firmware. These scales are WAY too slow in their response time and do not seem to be widespread. Custom firmware can be written (I probably will write it for a friend who has these scales) and it'd great to be able to support as many scales as possible!

Regards,

Brian

Brian