Wednesday 31 March 2021

Setting the homing move parameters - and sneaky GUI button macros

X Axis Homing parameters:

Struggled a bit with this, despite having spent some time with it a week or so ago. Here's the crux of what I've got, having done a lot more trial and error ("playing") with the settings:

MIN_LIMIT = -100


HOME = 0.000

MIN_LIMIT = -100.0

# Duplicated?

  • HOME is where the axis moves - AFTER setting the home zero position
  • HOME_OFFSET is the offset between home switch and where machine zero is to be set
  • For some reason, we need to specify the limits in both [AXIS_X] and [JOINT_0]. Not clear why.
Here's what I ended up with:


HOME =                          0.000
FERROR =                        10
MIN_FERROR =                    1.00
MAX_VELOCITY =                  50
MAX_ACCELERATION =              100.0
BACKLASH =                      0.000
INPUT_SCALE =                   -200 
OUTPUT_SCALE =                  1.000
HOME_OFFSET =                   2.0

P =                             1.0
I =                             0.0 
D =                             0.0
FF0 =                           0.0
FF1 =                           1.0
FF2 =                           0.0
BIAS =                          0.0
DEADBAND =                      0.0
MAX_OUTPUT =                    0.0

STEPLEN    =                    2500
STEPSPACE  =                    2500  
STEP_SCALE =                    1000.0 

MIN_LIMIT =                     -100.0
MAX_LIMIT =                     1

Go Home (GUI button) and go_to_home.ngc macro:

I got confused about the "Go Home" button in the GUI and the above homing parameters. What I overlooked is that the GUI buttons mainly just call up macros from the subroutines subfolder  in the Probe Basic Lathe folder.

Here's what the go_to_home.ngc macro looks like. Nothing special really:

O<go_to_home> sub

G0 G53
; G53 G0 Z0
G53 G0 X0

O<go_to_home> endsub


It simply tells the machine to go to machine coords X0 and Z0. Clearly, X0 and Z0 need to lie within the soft limits for this to work out. I've also commented out the Z0 move, since I haven't set up the Z homing moves yet - on account of the fact that I haven't fitted any homing / limit switches.

Sunday 28 March 2021

Connect up the 7i85 - get X & Z encoders working - SUCCESS!

I need to enable the additional encoders - for the X and Z axes - as I am planning to use them to close the position control loop. 

Telling LinuxCNC to expect more encoders:
Initially I told LinuxCNC that I have only one encoder on the machine (the spindle encoder in the 7i76) so firstly I will need to change this line in the main hal file:


loadrt [EMCMOT]EMCMOT servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[KINS]JOINTS
loadrt hostmot2
loadrt hm2_pci config=" num_encoders=4 num_pwmgens=0 num_stepgens=2 sserial_port_0=00xxxx"
setp hm2_5i25.0.watchdog.timeout_ns 5000000
loadrt pid names=pid.x,pid.z,pid.s

Then the encoders can be seen within halshow:


Note that encoder #01 is the "dummy" twin for the spindle encoder. It can't be used but it seems you have to count it as one of your required encoders. So the first encoder on the 7i85 board is actually encoder #02. I have that down as the X axis (cross slide), so the Z axis is going to be encoder #03. This is one of those foibles that's designed to catch out noobs like me. Luckily Mr Mesa helped on that one before I wasted too much time.

Drawing the magnetic strip past the read head generates the position signal shown. That's a good start at least.

Fitting the encoder and magnetic strip:
Now let's fix the encoder read head to the saddle body and attach the magnetic strip to the underside of the cross slide.

Wow - look at those super horney timing pulleys!!

I previously machined the underside to take the strip so it wouldn't foul the read head. This needs to be nice and clean, as it uses a self adhesive backing.

Like this. There's also a thing stainless steel cover strip that fits over the top. Yes, the read head "sees" the magnetic strip through that.

Then refit it and......check it actually works. Yes! Now to set it up...

HAL and INI file changes:
In order to use closed loop positional feedback, you obviously need the encoder and servo to speak the same language when it comes to distances.

The encoder is a "5um" scale ie the fundamental distance between markers is 20um but with a quadrature signal, you can resolve 4 times that. So the encoder scale factor is 200 "counts per machine unit" (mm).

The servo is set up for 2500 steps per rev (in the servo drive) and is driving a 5mm pitch ballscrew through a 2:1 reduction drive (16t:32t timing pulleys, remember?). So we have 1000 "steps per machine unit" (mm). 

The output from the stepgen component is a direct position in mm. But the output from the encoder position is encoder counts. In my case, I have a "5um" encoder scale, so that equates to 200 counts per machine unit. Or in fact -200 counts per machine unit, since the encoder counts down as the position increases.

I need to scale the encoder output to match the stepgen output. Turns out you need to set the scale factor with this line. It picks up the value of INPUT_SCALE (here -200) and applies it to the encoder driver. This was the missing element.

setp    hm2_5i25.0.encoder.02.scale [JOINT_0]INPUT_SCALE
Then the output of the encoder position pin matches the output. Whoopee - and the encoder feedback works!

Finally, the PID parameters need to be dialled right back. The initial P term is 1000(!!), so it seems to make sense to set that to 1.0, while the I and D are already set at zero.

Encoder repair - bulb replacement

What up?
The spindle encoder I spent ages fitting to the Bantam either never worked or has since demised, possibly due to rough handling on my part. I DID check the spindle encoder but I forget the specifics.

Certainly, trying to talk to it using Halshow is a fruitless effort. The circuit is getting power and there is some sort of voltage on most of the outputs. Main issue is that none of them actually change state. That's a bit of an issue in an encoder.

Let's take the bugger apart:
Can't be difficult to figure out WTF is happening, or not as the case may be.

Sure enough, the mechanical bits comprise an optically slotted glass wheel with a similar slotted (stationary) grid providing a sort of Vernier effect. 

It's lit from below through a simple lens with a 5V incandescent bulb the size of a matchstick head. Or was until the filament burnt out. There's also some sort of flat optical receiver for the A, B and Z outputs.

Beyond that, there's a quad comparator and a couple of RS422 differential line drivers. Looks to me as if replacing the light source would be "all" that's required.

Here's the light source.

It's just a simple incandescent bulb of 3mm diameter, straight across the 5V supply.

How to fix it?
I found some of those tape LEDs. The package included a 12V battery with a switch and a single segment (3 LEDS per segment) wired up for sales purposes. This showed me that the forward voltage is about 3V under the recommended(?) current. I also measured 2.5V across the 150 Ohm resistor, suggesting a current of 17mA or so. Given that I have around 5V in the encoder supply, simply reusing this 150 Ohm with a single LED would result in around 13mA or so, a cunning plan came to be.

I snipped out one of the LEDs that was neighbouring the resistor and cut back the flex PCB to fit in the cavity where the bulb had been. I also cut and filed the cavity to get the LED roughly where the filament had been, then glued it in place with Araldite Rapid. With a layer of Krapton tape underneath for electrical isolation, it fits back into the original location. This was a bit of an act of faith, as it was only when I powered it up that I could be certain it actually worked. Which it did.

Obvs I couldn't move on without fiddling with the 3 pots. only one channel worked, so I assume the circuit is sensitive to the brightness to some degree. There's one per channel and there seems to be a sweet zone where the comparators do their thing. With all 3 in the middle of their zones,  I seem to have a result.

Pleased with this, as the same encoders are used on the 3 axes of The Shiz. This one came with in the bag of spares and claimed (correctly) to be faulty. It's now going to serve as the spindle encoder on the Bantam.


Let's call that job done. And yes, it works in LinuxCNC.

Friday 26 March 2021

Closing the loop with my linear encoders. Hal file changes.

Let's see what I've got, now that I think I've got the 5i25 set up to support a 7i76 and a 7i85. I'm going to want to connect up a couple of linear encoders soon, one for each of the X and Z axes. The spindle (rotary) encoder is natively supported by the 7i76.

This is how to show the hal "pins" that have been generated:

loadrt hostmot2
loadrt hm2_pci
show pin
Component Pins:
Owner   Type  Dir         Value  Name
(7i76 - 32 inputs):
     7  s32  OUT             0  hm2_5i25.0.0.debug
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-00
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-00-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-01
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-01-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-02
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-02-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-03
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-03-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-04
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-04-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-05
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-05-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-06
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-06-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-07
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-07-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-08
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-08-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-09
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-09-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-10
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-10-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-11
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-11-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-12
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-12-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-13
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-13-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-14
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-14-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-15
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-15-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-16
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-16-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-17
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-17-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-18
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-18-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-19
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-19-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-20
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-20-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-21
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-21-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-22
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-22-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-23
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-23-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-24
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-24-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-25
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-25-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-26
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-26-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-27
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-27-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-28
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-28-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-29
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-29-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-30
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-30-not
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-31
     7  bit   OUT         FALSE  hm2_5i25.0.7i76.0.0.input-31-not
(7i76 - 16 outputs):
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-00
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-01
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-02
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-03
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-04
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-05
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-06
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-07
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-08
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-09
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-10
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-11
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-12
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-13
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-14
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.output-15
(7i76 - spindle control outputs):
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.spindir
     7  bit   IN          FALSE  hm2_5i25.0.7i76.0.0.spinena
     7  float IN              0  hm2_5i25.0.7i76.0.0.spinout
(Encoders - there seem to be 6??):
     7  s32   OUT             0  hm2_5i25.0.encoder.00.count
     7  s32   OUT             0  hm2_5i25.0.encoder.00.count-latched
     7  bit   I/O         FALSE  hm2_5i25.0.encoder.00.index-enable
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.00.input-a
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.00.input-b
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.00.input-index
     7  bit   IN          FALSE  hm2_5i25.0.encoder.00.latch-enable
     7  bit   IN          FALSE  hm2_5i25.0.encoder.00.latch-polarity
     7  float OUT             0  hm2_5i25.0.encoder.00.position
     7  float OUT             0  hm2_5i25.0.encoder.00.position-latched
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.00.quad-error
     7  bit   IN          FALSE  hm2_5i25.0.encoder.00.quad-error-enable
     7  s32   OUT             0  hm2_5i25.0.encoder.00.rawcounts
     7  s32   OUT             0  hm2_5i25.0.encoder.00.rawlatch
     7  bit   IN          FALSE  hm2_5i25.0.encoder.00.reset
     7  float OUT             0  hm2_5i25.0.encoder.00.velocity
     7  float OUT             0  hm2_5i25.0.encoder.00.velocity-rpm
     7  s32   OUT             0  hm2_5i25.0.encoder.01.count
     7  s32   OUT             0  hm2_5i25.0.encoder.01.count-latched
     7  bit   I/O         FALSE  hm2_5i25.0.encoder.01.index-enable
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.01.input-a
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.01.input-b
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.01.input-index
     7  bit   IN          FALSE  hm2_5i25.0.encoder.01.latch-enable
     7  bit   IN          FALSE  hm2_5i25.0.encoder.01.latch-polarity
     7  float OUT             0  hm2_5i25.0.encoder.01.position
     7  float OUT             0  hm2_5i25.0.encoder.01.position-latched
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.01.quad-error
     7  bit   IN          FALSE  hm2_5i25.0.encoder.01.quad-error-enable
     7  s32   OUT             0  hm2_5i25.0.encoder.01.rawcounts
     7  s32   OUT             0  hm2_5i25.0.encoder.01.rawlatch
     7  bit   IN          FALSE  hm2_5i25.0.encoder.01.reset
     7  float OUT             0  hm2_5i25.0.encoder.01.velocity
     7  float OUT             0  hm2_5i25.0.encoder.01.velocity-rpm
     7  s32   OUT             0  hm2_5i25.0.encoder.02.count
     7  s32   OUT             0  hm2_5i25.0.encoder.02.count-latched
     7  bit   I/O         FALSE  hm2_5i25.0.encoder.02.index-enable
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.02.input-a
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.02.input-b
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.02.input-index
     7  bit   IN          FALSE  hm2_5i25.0.encoder.02.latch-enable
     7  bit   IN          FALSE  hm2_5i25.0.encoder.02.latch-polarity
     7  float OUT             0  hm2_5i25.0.encoder.02.position
     7  float OUT             0  hm2_5i25.0.encoder.02.position-latched
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.02.quad-error
     7  bit   IN          FALSE  hm2_5i25.0.encoder.02.quad-error-enable
     7  s32   OUT             0  hm2_5i25.0.encoder.02.rawcounts
     7  s32   OUT             0  hm2_5i25.0.encoder.02.rawlatch
     7  bit   IN          FALSE  hm2_5i25.0.encoder.02.reset
     7  float OUT             0  hm2_5i25.0.encoder.02.velocity
     7  float OUT             0  hm2_5i25.0.encoder.02.velocity-rpm
     7  s32   OUT             0  hm2_5i25.0.encoder.03.count
     7  s32   OUT             0  hm2_5i25.0.encoder.03.count-latched
     7  bit   I/O         FALSE  hm2_5i25.0.encoder.03.index-enable
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.03.input-a
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.03.input-b
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.03.input-index
     7  bit   IN          FALSE  hm2_5i25.0.encoder.03.latch-enable
     7  bit   IN          FALSE  hm2_5i25.0.encoder.03.latch-polarity
     7  float OUT             0  hm2_5i25.0.encoder.03.position
     7  float OUT             0  hm2_5i25.0.encoder.03.position-latched
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.03.quad-error
     7  bit   IN          FALSE  hm2_5i25.0.encoder.03.quad-error-enable
     7  s32   OUT             0  hm2_5i25.0.encoder.03.rawcounts
     7  s32   OUT             0  hm2_5i25.0.encoder.03.rawlatch
     7  bit   IN          FALSE  hm2_5i25.0.encoder.03.reset
     7  float OUT             0  hm2_5i25.0.encoder.03.velocity
     7  float OUT             0  hm2_5i25.0.encoder.03.velocity-rpm
     7  s32   OUT             0  hm2_5i25.0.encoder.04.count
     7  s32   OUT             0  hm2_5i25.0.encoder.04.count-latched
     7  bit   I/O         FALSE  hm2_5i25.0.encoder.04.index-enable
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.04.input-a
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.04.input-b
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.04.input-index
     7  bit   IN          FALSE  hm2_5i25.0.encoder.04.latch-enable
     7  bit   IN          FALSE  hm2_5i25.0.encoder.04.latch-polarity
     7  float OUT             0  hm2_5i25.0.encoder.04.position
     7  float OUT             0  hm2_5i25.0.encoder.04.position-latched
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.04.quad-error
     7  bit   IN          FALSE  hm2_5i25.0.encoder.04.quad-error-enable
     7  s32   OUT             0  hm2_5i25.0.encoder.04.rawcounts
     7  s32   OUT             0  hm2_5i25.0.encoder.04.rawlatch
     7  bit   IN          FALSE  hm2_5i25.0.encoder.04.reset
     7  float OUT             0  hm2_5i25.0.encoder.04.velocity
     7  float OUT             0  hm2_5i25.0.encoder.04.velocity-rpm
     7  s32   OUT             0  hm2_5i25.0.encoder.05.count
     7  s32   OUT             0  hm2_5i25.0.encoder.05.count-latched
     7  bit   I/O         FALSE  hm2_5i25.0.encoder.05.index-enable
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.05.input-a
     7  bit   OUT          TRUE  hm2_5i25.0.encoder.05.input-b
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.05.input-index
     7  bit   IN          FALSE  hm2_5i25.0.encoder.05.latch-enable
     7  bit   IN          FALSE  hm2_5i25.0.encoder.05.latch-polarity
     7  float OUT             0  hm2_5i25.0.encoder.05.position
     7  float OUT             0  hm2_5i25.0.encoder.05.position-latched
     7  bit   OUT         FALSE  hm2_5i25.0.encoder.05.quad-error
     7  bit   IN          FALSE  hm2_5i25.0.encoder.05.quad-error-enable
     7  s32   OUT             0  hm2_5i25.0.encoder.05.rawcounts
     7  s32   OUT             0  hm2_5i25.0.encoder.05.rawlatch
     7  bit   IN          FALSE  hm2_5i25.0.encoder.05.reset
     7  float OUT             0  hm2_5i25.0.encoder.05.velocity
     7  float OUT             0  hm2_5i25.0.encoder.05.velocity-rpm
     7  u32   IN     0x007F2815  hm2_5i25.0.encoder.muxed-sample-frequency
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.000.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.001.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.002.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.003.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.004.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.005.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.006.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.007.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.008.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.009.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.010.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.011.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.012.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.012.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.013.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.013.out
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.014.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.015.in_not
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.016.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.017.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.017.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.018.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.018.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.019.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.019.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.020.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.020.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.021.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.021.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.022.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.022.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.023.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.023.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.024.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.024.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.025.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.025.out
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.026.in_not
     7  bit   IN          FALSE  hm2_5i25.0.gpio.026.out
     7  bit   OUT         FALSE
     7  bit   OUT          TRUE  hm2_5i25.0.gpio.027.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.028.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.029.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.030.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.031.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.032.in_not
     7  bit   OUT          TRUE
     7  bit   OUT         FALSE  hm2_5i25.0.gpio.033.in_not
     7  bit   IN          FALSE  hm2_5i25.0.led.CR01
     7  bit   IN          FALSE  hm2_5i25.0.led.CR02
     7  s32   OUT             0
     7  s32   OUT             0  hm2_5i25.0.read_gpio.time
     7  u32   OUT    0x00000000  hm2_5i25.0.sserial.port-0.fault-count
     7  u32   OUT    0x00000000  hm2_5i25.0.sserial.port-0.port_state
     7  u32   OUT    0x00000000  hm2_5i25.0.sserial.port-0.port_state2
     7  u32   OUT    0x00000000  hm2_5i25.0.sserial.port-0.port_state3
     7  bit   IN           TRUE
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.00.control-type
(5 step generators):
     7  s32   OUT             0  hm2_5i25.0.stepgen.00.counts
     7  float OUT             0  hm2_5i25.0.stepgen.00.dbg_err_at_match
     7  float OUT             0  hm2_5i25.0.stepgen.00.dbg_ff_vel
     7  float OUT             0  hm2_5i25.0.stepgen.00.dbg_pos_minus_prev_cmd
     7  float OUT             0  hm2_5i25.0.stepgen.00.dbg_s_to_match
     7  s32   OUT             0  hm2_5i25.0.stepgen.00.dbg_step_rate
     7  float OUT             0  hm2_5i25.0.stepgen.00.dbg_vel_error
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.00.enable
     7  float IN              0  hm2_5i25.0.stepgen.00.position-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.00.position-fb
     7  float IN              0  hm2_5i25.0.stepgen.00.velocity-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.00.velocity-fb
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.01.control-type
     7  s32   OUT             0  hm2_5i25.0.stepgen.01.counts
     7  float OUT             0  hm2_5i25.0.stepgen.01.dbg_err_at_match
     7  float OUT             0  hm2_5i25.0.stepgen.01.dbg_ff_vel
     7  float OUT             0  hm2_5i25.0.stepgen.01.dbg_pos_minus_prev_cmd
     7  float OUT             0  hm2_5i25.0.stepgen.01.dbg_s_to_match
     7  s32   OUT             0  hm2_5i25.0.stepgen.01.dbg_step_rate
     7  float OUT             0  hm2_5i25.0.stepgen.01.dbg_vel_error
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.01.enable
     7  float IN              0  hm2_5i25.0.stepgen.01.position-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.01.position-fb
     7  float IN              0  hm2_5i25.0.stepgen.01.velocity-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.01.velocity-fb
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.02.control-type
     7  s32   OUT             0  hm2_5i25.0.stepgen.02.counts
     7  float OUT             0  hm2_5i25.0.stepgen.02.dbg_err_at_match
     7  float OUT             0  hm2_5i25.0.stepgen.02.dbg_ff_vel
     7  float OUT             0  hm2_5i25.0.stepgen.02.dbg_pos_minus_prev_cmd
     7  float OUT             0  hm2_5i25.0.stepgen.02.dbg_s_to_match
     7  s32   OUT             0  hm2_5i25.0.stepgen.02.dbg_step_rate
     7  float OUT             0  hm2_5i25.0.stepgen.02.dbg_vel_error
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.02.enable
     7  float IN              0  hm2_5i25.0.stepgen.02.position-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.02.position-fb
     7  float IN              0  hm2_5i25.0.stepgen.02.velocity-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.02.velocity-fb
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.03.control-type
     7  s32   OUT             0  hm2_5i25.0.stepgen.03.counts
     7  float OUT             0  hm2_5i25.0.stepgen.03.dbg_err_at_match
     7  float OUT             0  hm2_5i25.0.stepgen.03.dbg_ff_vel
     7  float OUT             0  hm2_5i25.0.stepgen.03.dbg_pos_minus_prev_cmd
     7  float OUT             0  hm2_5i25.0.stepgen.03.dbg_s_to_match
     7  s32   OUT             0  hm2_5i25.0.stepgen.03.dbg_step_rate
     7  float OUT             0  hm2_5i25.0.stepgen.03.dbg_vel_error
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.03.enable
     7  float IN              0  hm2_5i25.0.stepgen.03.position-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.03.position-fb
     7  float IN              0  hm2_5i25.0.stepgen.03.velocity-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.03.velocity-fb
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.04.control-type
     7  s32   OUT             0  hm2_5i25.0.stepgen.04.counts
     7  float OUT             0  hm2_5i25.0.stepgen.04.dbg_err_at_match
     7  float OUT             0  hm2_5i25.0.stepgen.04.dbg_ff_vel
     7  float OUT             0  hm2_5i25.0.stepgen.04.dbg_pos_minus_prev_cmd
     7  float OUT             0  hm2_5i25.0.stepgen.04.dbg_s_to_match
     7  s32   OUT             0  hm2_5i25.0.stepgen.04.dbg_step_rate
     7  float OUT             0  hm2_5i25.0.stepgen.04.dbg_vel_error
     7  bit   IN          FALSE  hm2_5i25.0.stepgen.04.enable
     7  float IN              0  hm2_5i25.0.stepgen.04.position-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.04.position-fb
     7  float IN              0  hm2_5i25.0.stepgen.04.velocity-cmd
     7  float OUT             0  hm2_5i25.0.stepgen.04.velocity-fb
     7  bit   I/O         FALSE  hm2_5i25.0.watchdog.has_bit
     7  s32   OUT             0  hm2_5i25.0.write.time
     7  s32   OUT             0  hm2_5i25.0.write_gpio.time

WTF?? I wasn't expecting to see so many encoders and GPIO. It looks like 12 GPIO inputs and 22(?) GPIO outputs. And apparently 6 encoders?

No, mate. No. Not quite.

Those First 2 are actually the 7i76 encoder - plus a dummy (encoders 0 & 1). Then we have 4 actual encoder channels in the 7i85 (encoders 2, 3 &4. Apparently, encoder channels are multiplexed in pairs back to the FPGA in the 5i25.

Furthermore, the GPIO pins are reported, even though they are already allocated to the encoders, RS-422 channels etc.

A better way to report how the daughtercards are set up is to give it some of this:

sudo mesaflash --device 5i25 --readhmid

...which gives the following:

Configuration pin-out:
IO Connections for P3
Pin# I/O Pri. func Sec. func Chan Pin func Pin Dir
1 0 IOPort StepGen 0 Dir/Table2 (Out)
14 1 IOPort StepGen 0 Step/Table1 (Out)
2 2 IOPort StepGen 1 Dir/Table2 (Out)
15 3 IOPort StepGen 1 Step/Table1 (Out)
3 4 IOPort StepGen 2 Dir/Table2 (Out)
16 5 IOPort StepGen 2 Step/Table1 (Out)
4 6 IOPort StepGen 3 Dir/Table2 (Out)
17 7 IOPort StepGen 3 Step/Table1 (Out)
5 8 IOPort StepGen 4 Dir/Table2 (Out)
6 9 IOPort StepGen 4 Step/Table1 (Out)
7 10 IOPort SSerial 0 TXData0 (Out)
8 11 IOPort SSerial 0 RXData0 (In)
9 12 IOPort SSerial 0 TXData1 (Out)
10 13 IOPort SSerial 0 RXData1 (In)
11 14 IOPort MuxedQCount 0 MuxQ-IDX (In)
12 15 IOPort MuxedQCount 0 MuxQ-B (In)
13 16 IOPort MuxedQCount 0 MuxQ-A (In)
IO Connections for P2
Pin# I/O Pri. func Sec. func Chan Pin func Pin Dir
1 17 IOPort SSerial 0 RXData6 (In)
14 18 IOPort SSerial 0 TXData6 (Out)
2 19 IOPort SSerial 0 RXData5 (In)
15 20 IOPort SSerial 0 TXData5 (Out)
3 21 IOPort SSerial 0 RXData4 (In)
16 22 IOPort SSerial 0 TXData4 (Out)
4 23 IOPort SSerial 0 RXData3 (In)
17 24 IOPort SSerial 0 TXData3 (Out)
5 25 IOPort SSerial 0 RXData2 (In)
6 26 IOPort SSerial 0 TXData2 (Out)
7 27 IOPort MuxedQCountSel 2 MuxSel0 (Out)
8 28 IOPort MuxedQCount 1 MuxQ-A (In)
9 29 IOPort MuxedQCount 1 MuxQ-B (In)
10 30 IOPort MuxedQCount 1 MuxQ-IDX (In)
11 31 IOPort MuxedQCount 2 MuxQ-A (In)
12 32 IOPort MuxedQCount 2 MuxQ-B (In)
13 33 IOPort MuxedQCount 2 MuxQ-IDX (In)

"Mesaflash shows all the hardware (its showing 6 encoders here)
Muxed encoders share a set of pins for 2 encoders
Muxed encoder 0 on the 7I76 = hal encoders 0 and 1 (1 is a dummy)
Muxed encoders 1 and 2 on the 7I85 = hal encoders 2,3,4,5"

Sort of makes sense now!

So - what to do?

Something like this? The X.....

# ---Encoder feedback signals/setup---

setp    hm2_7i76e.0.encoder.02.counter-mode 0
setp    hm2_7i76e.0.encoder.02.filter 1
setp    hm2_7i76e.0.encoder.02.index-invert 0
setp    hm2_7i76e.0.encoder.02.index-mask 0
setp    hm2_7i76e.0.encoder.02.index-mask-invert 0
setp    hm2_7i76e.0.encoder.02.scale  [JOINT_0]ENCODER_SCALE

net x-pos-fb               <=  hm2_7i76e.0.encoder.02.position
net x-vel-fb               <=  hm2_7i76e.0.encoder.02.velocity
net x-pos-fb               =>  joint.0.motor-pos-fb
net x-index-enable    joint.0.index-enable  <=>  hm2_7i76e.0.encoder.02.index-enable
net x-pos-rawcounts        <=  hm2_7i76e.0.encoder.02.rawcounts

...and the corresponding Y?

# ---Encoder feedback signals/setup---

setp    hm2_7i76e.0.encoder.01.counter-mode 0
setp    hm2_7i76e.0.encoder.01.filter 1
setp    hm2_7i76e.0.encoder.01.index-invert 0
setp    hm2_7i76e.0.encoder.01.index-mask 0
setp    hm2_7i76e.0.encoder.01.index-mask-invert 0
setp    hm2_7i76e.0.encoder.01.scale  [JOINT_1]ENCODER_SCALE

net y-pos-fb               <=  hm2_7i76e.0.encoder.01.position
net y-vel-fb               <=  hm2_7i76e.0.encoder.01.velocity
net y-pos-fb               =>  joint.1.motor-pos-fb
net y-index-enable    joint.1.index-enable  <=>  hm2_7i76e.0.encoder.01.index-enable
net y-pos-rawcounts        <=  hm2_7i76e.0.encoder.01.rawcounts

Or this (X)?

# ---Encoder feedback signals/setup---

setp hm2_7i76e.0.encoder.01.counter-mode 0
setp hm2_7i76e.0.encoder.01.filter 1
setp hm2_7i76e.0.encoder.01.index-invert 0
setp hm2_7i76e.0.encoder.01.index-mask 0
setp hm2_7i76e.0.encoder.01.index-mask-invert 0
setp hm2_7i76e.0.encoder.01.scale [JOINT_0]ENCODER_SCALE

net x-pos-fb <= hm2_7i76e.0.encoder.01.position
net x-vel-fb <= hm2_7i76e.0.encoder.01.velocity
net x-pos-fb => joint.0.motor-pos-fb
net x-index-enable joint.0.index-enable <=> hm2_7i76e.0.encoder.01.index-enable

net x-pos-rawcounts <= hm2_7i76e.0.encoder.01.rawcounts 

Interesting post about linear encoder feedback:

"Therefore it is important that the scale and servo position are the same. Otherwise one always runs after the other and it also vibrates. Check that by switching off the scale.

With encoder off:
#net x-pos-fb   <=  hm2_7i95.0.encoder.00.position	# Encoderpostion to PIN x-pos-fb
With stepgen feedback active:
net x-pos-fb     <= hm2_7i95.0.stepgen.00.position-fb	# Stepgenposition to PIN x-pos-fb

Then compare encoder position and step position. They have to be the same if not adjust your scale parameters. Verify the whole thing with a dial indicator.

Other things. Your servo and amplifier already have their own control loop with KP parameter. It is a good idea to tune this control loop and keep KP in linuxcnc as low as possible.

Finally turn on your scale and it will work.

The following error can be found in joint.0.f-error or using halscope."

This is what I will try:
# Default FB from stepgen:
net x-pos-fb <= hm2_5i25.0.stepgen.00.position-fb # Stepgenposition to PIN x-pos-fb
# Alternative FB from encoder:
# net x-pos-fb <= hm2_5i25.0.encoder.02.position # Encoderposition to PIN x-pos-fb

# Default FB from stepgen:
net z-pos-fb <= hm2_5i25.0.stepgen.01.position-fb # Stepgenposition to PIN z-pos-fb
# Alternative FB from encoder:
# net z-pos-fb <= hm2_5i25.0.encoder.03.position # Encoderposition to PIN z-pos-fb

It still starts up - but does it actually report position correctly? be continued....

Final assembly and test of the spindle nose adaptor - RESULT!!

After the recent distraction caused by the 3D scanner, resurrecting the 3D printer and buggering about with the throttle bodies for my Honda...