Modbus input for absolute encoder position?

Andy that is interesting! I certainly wish I had you and PCW's knowledge level on these things...lol. I need to find a good starting point to start learning. Any recommendations? I know literally nothing in the programming side.. and not sure what would be best to begin learning.... Baby step method..

Chris

No eBay APP ID and/or Cert ID defined in Kunena configurationI think that the first thing to try would be mb2hal to at least see if you can get the data from the drives.

linuxcnc.org/docs/devel/html/drivers/mb2hal.html

For the hardware interface, something like this:


There are lots on there. But get one with 3 terminals so you can connect GND.

.......realtime sum2 module ? what's that? go too Heidenhain Endat Encoders ?
Hardware-interface is:SEW Eurodrive DFE33B
download.sew-eurodrive.com/download/pdf/16725611.pdf

Weiler810T wrote: .......realtime sum2 module ? what's that?

linuxcnc.org/docs/2.7/html/man/man9/sum2.9.html

It's one of many HAL modules, all listed here under "Realtime components and kernel modules"
linuxcnc.org/docs/2.7/html/

Hello,

I recently purchased servo drives with multiturn / absolute encoders. I am able to read the required registers via MB2HAL.

Multiturn Count: 0 - 65536
Pulses per Turn: 0 - 65536

I was wondering if anybody was able to get this to work in LCNC as PCW/andypugh described? ModBus absolute position read at startup and then incremental encoders for realtime feedback.

Regards,
Markus

0x2102 wrote: Multiturn Count: 0 - 65536
Pulses per Turn: 0 - 65536

I was wondering if anybody was able to get this to work in LCNC as PCW/andypugh described? ModBus absolute position read at startup and then incremental encoders for realtime feedback.

I think it might be simpler than you think. You should be able to just add the numbers together in HAL and use directly.

Note that the sum2 HAL component has separate gains for the two inputs, so you can scale one for distance-per-turn and the other for distance-per-pulse.
You might need to convert from signed integer (S32) to Floating point, but that, plus specifying absolute encoder homing should be all that you need.
(This assumes you are reading the Modbus in a realtime thread, of course)