Absolute Encoder Questions / SSI via 5i25

First I connected the encoder the opposite way to yours. It responded, though only one normal response and then 0x01FFFFFF. I had to take it away from the magnetic stripe and set again, then it would give one normal response and so on.

I just switched the wires and it looks better, the normal response comes every read cycle. But I'm not sure about the binary output. Or I might decode wrong (I've made a gray_to_abs component from the wikipedia code)


Not sure at all that it's correct, is unsigned ok here?

What is the simplest way to send write_strobe each servo period? I tried to connect stepgen to write_strobe but then I can't set the SSI parameters. Some switch is nesessary, it gets a bit complicated. I probably have to try connecting stepgen in postgui_hal

Great news! I will try it asap, hopefully today or tomorrow.

No abs_encoder in rtlib.
Make log:

make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-122-rtai'
/home/pkm/linuxcnc-dev/src/hal/drivers/mesa-hostmot2/abs_encoder.c: In function `hm2_absenc_parse_md`:
/home/pkm/linuxcnc-dev/src/hal/drivers/mesa-hostmot2/abs_encoder.c:147: warning: passing argument 2 of ˜`hal_export_funct` from incompatible pointer type
/home/pkm/linuxcnc-dev/src/hal/hal.h:621: note: expected void (*)(void *, long int) but argument is of type `˜void (*)(struct hostmot2_t *)`

I use run-in-place. But just no abs_encoder in rtlib folder, and loadrt abs_encoder causes error

5i25_7i76.hal:9: Can't find module 'abs_encoder' in /home/pkm/linuxcnc-dev/rtlib

Sure I did everything.

./autogen.sh
./configure --enable-run-in-place
make
sudo make setuid
. ./scripts/rip-environment
linuxcnc

The patch was OK, at least there's abs_encoder.c in its folder, abs_encoder strings in src/makefile.

Actually I first tried adding
addf hm2_5i25.0.trigger_encoders servo-thread

and received error
HAL: ERROR: function 'hm2_5i25.0.trigger_encoders' not found
5i25_7i76.hal:12: addf failed

And then I thought addf needs loadrt and started that loadrt abs_encoder thing.

Without addf it starts, I see absenc 00 and 01.
I'll try to set some parameters now.

OK, I started config with
addf hm2_trigger_encoders servo-thread

and I'm flooded with popping errors
hm2/hm2_5i25.0: Data transmission not complete before encoder position read. You may need to place the absenc_trigger function earlier in the thread

Also, I can't find absenc.num_instances parameter in the tree.

upd: Looks like it's hm2_pci call parameter num_absencs

I've set some parameters

setp hm2_5i25.0.absenc.00.bit-length 25
setp hm2_5i25.0.absenc.00.frequency-khz 50
setp hm2_5i25.0.absenc.00.gray-code 1

Still flooded with earlier-in-the-thread errors, so the machine starts 30 seconds.
And looks like no actual readings from the encoder.

Other settings nesessary?

50 KHz is _way_ too slow especially if you expect the SSI read to be
finished by the end of the other hostmot2 reads (24 bit x 20 usec = 480 uSec!)

In fact my encoder will not even read at that rate as the
SSI reset time is ~20 usec so it just resets every clock