Encoder on 7i95t

Hello everyone,I’m currently working with LinuxCNC on a Pi5 with a Mesa 7i95T. After getting the configuration for the motors and limit switches working, I’m now trying to set up the encoders (currently just for the X-axis). Unfortunately, I’m still relatively new to this, and I find the .hal configuration a bit overwhelming.
I’m getting the following error when starting up:

Debug file information:
Note: Using POSIX realtime
./main.hal:121: Pin 'joint.0.motor-pos-fb' was already linked to signal 'joint-0-pos-fb'
19234


I’ve attached my .ini and .hal files. Could someone please help me understand which inputs need to be connected where?Thanks in advance for your time and assistance

delete the red text

and change lines like

net joint-0-pos-fb <= hm2_[MESA](BOARD).0.stepgen.00.position-fb

to net joint-0-pos-fb <= hm2_[MESA](BOARD).0.encoder.00.position

If you want encoder feedback (closed loop) rather than stepgen feedback (open loop)





# position command and feedback
net joint-0-pos-cmd <= joint.0.motor-pos-cmd
net joint-0-pos-cmd => pid.x.command

net joint-0-pos-fb <= hm2_[MESA](BOARD).0.stepgen.00.position-fb
net joint-0-pos-fb => joint.0.motor-pos-fb
net joint-0-pos-fb => pid.x.feedback

# PID Output
net joint.0.output <= pid.x.output
net joint.0.output => hm2_[MESA](BOARD).0.stepgen.00.velocity-cmd

# ENOCODER
setp hm2_[MESA](BOARD).0.encoder.00.counter-mode 0
setp hm2_[MESA](BOARD).0.encoder.00.filter 1
setp hm2_[MESA](BOARD).0.encoder.00.index-invert 0
setp hm2_[MESA](BOARD).0.encoder.00.index-mask 0
setp hm2_[MESA](BOARD).0.encoder.00.index-mask-invert 0
setp hm2_[MESA](BOARD).0.encoder.00.scale [JOINT_0](ENCODER_SCALE)

net x-pos-fb <= hm2_[MESA](BOARD).0.encoder.00.position
net x-vel-fb <= hm2_[MESA](BOARD).0.encoder.00.velocity
net x-pos-fb => joint.0.motor-pos-fb
net x-index-enable joint.0.index-enable <=> hm2_[MESA](BOARD).0.encoder.00.in
net x-pos-rawcounts <= hm2_[MESA](BOARD).0.encoder.00.rawcounts

# Home
net home-x => joint.0.home-sw-in
net x-neg-limit => joint.0.neg-lim-sw-in
net x-pos-limit => joint.0.pos-lim-sw-in

I got the machine to open now.
But when i try to home the axis it gives me a "Joint.0 following error"

Attaching my current X set-up here.
I'd be greatful if anybody finds some time to look over it!

CODE:
#**********************************************
# X Axis (Joint: 0 / Output: 0)
#**********************************************

# PID Setup
setp pid.x.Pgain [JOINT_0](P)
setp pid.x.Igain [JOINT_0](I)
setp pid.x.Dgain [JOINT_0](D)
setp pid.x.bias [JOINT_0](BIAS)
setp pid.x.FF0 [JOINT_0](FF0)
setp pid.x.FF1 [JOINT_0](FF1)
setp pid.x.FF2 [JOINT_0](FF2)
setp pid.x.deadband [JOINT_0](DEADBAND)
setp pid.x.maxoutput [JOINT_0](MAX_OUTPUT)
setp pid.x.error-previous-target True
# limit stepgen velocity corrections caused by position feedback jitter
setp pid.x.maxerror [JOINT_0](MAX_ERROR)

# joint-0 enable chain
net joint-0-index-enable <=> pid.x.index-enable
net joint-0-index-enable <=> joint.0.index-enable

net joint-0-enable <= joint.0.amp-enable-out
net joint-0-enable => pid.x.enable

net joint-0-enable => hm2_[MESA](BOARD).0.stepgen.00.enable

# Joint 0 Step Generator Settings
setp hm2_[MESA](BOARD).0.stepgen.00.dirsetup [JOINT_0](DIRSETUP)
setp hm2_[MESA](BOARD).0.stepgen.00.dirhold [JOINT_0](DIRHOLD)
setp hm2_[MESA](BOARD).0.stepgen.00.steplen [JOINT_0](STEPLEN)
setp hm2_[MESA](BOARD).0.stepgen.00.stepspace [JOINT_0](STEPSPACE)
setp hm2_[MESA](BOARD).0.stepgen.00.position-scale [JOINT_0](SCALE)
setp hm2_[MESA](BOARD).0.stepgen.00.maxvel [JOINT_0](STEPGEN_MAX_VEL)
setp hm2_[MESA](BOARD).0.stepgen.00.maxaccel [JOINT_0](STEPGEN_MAX_ACC)
setp hm2_[MESA](BOARD).0.stepgen.00.step_type 0
setp hm2_[MESA](BOARD).0.stepgen.00.control-type 1


# joint 0 pos/vel/fb
net joint.0-pos-cmd <= joint.0.motor-pos-cmd
net joint.0-pos-cmd => pid.x.command

net joint.0-pos-fb <= hm2_[MESA](BOARD).0.encoder.00.position
net joint.0-pos-fb => joint.0.motor-pos-fb
net joint.0-pos-fb => pid.x.feedback

net joint.0-vel-cmd <= joint.0.vel-cmd

net joint.0.output <= pid.x.output
net joint.0.output <= hm2_[MESA](BOARD).0.stepgen.00.velocity-cmd

net Joint.0-vel-fb <= hm2_[MESA](BOARD).0.encoder.00.velocity
net joint.0-pos-rawcounts <= hm2_[MESA](BOARD).0.encoder.00.rawcounts
net joint.0-index-enable <=> hm2_[MESA](BOARD).0.encoder.00.index-enable

# Encoder
setp hm2_7i95.0.encoder.00.counter-mode 0
setp hm2_7i95.0.encoder.00.filter 1
setp hm2_7i95.0.encoder.00.index-invert 0
setp hm2_7i95.0.encoder.00.index-mask 0
setp hm2_7i95.0.encoder.00.index-mask-invert 0
setp hm2_7i95.0.encoder.00.scale [JOINT_0](ENCODER_SCALE)


# Home
net home-x => joint.0.home-sw-in
net x-neg-limit => joint.0.neg-lim-sw-in
net x-pos-limit => joint.0.pos-lim-sw-in

Did you first verify that stepgen feedback worked?
(scaled properly and motion in the correct directions)

That is replace:

net joint.0-pos-fb <= hm2_[MESA](BOARD).0.encoder.00.position

with:

net joint.0-pos-fb <= hm2_[MESA](BOARD).0.stepgen.00.position

Once this works, I would verify that the encoder position is also in the correct direction
and scaled properly.

Also note that for initial tuning with encoder feedback, you will need to widen the following
error limits and reduce the P term

 

Morning,

I replaced "encoder.00.position" with "stepgen.00.position-fb", which worked fine.

Then I checked the encoder and realized that it was counting in the negative direction when moving in positive coordinates. So, I added a minus sign in front of the stepper count in my .ini.
Now, the axis moves during the first part of the homing process. However, as soon as it hits the home switch for the first time which then tells it to change directions a "following Error" occurs.

Sorry, I don't really understand what you're trying to tell me with that.

My home search_vel is -0.5 and the latch_vel is -0.25.
And P is set on 10

Also if you use encoder feedback you will need to tune the system
and this requires increasing the following error limits:

FERROR = 0.005
MIN_FERROR = 0.0025

I would increase these to say

FERROR = 1

MIN_FERROR = .25

So you don't get nuisance following errors when tuning

Tuning involves using halscope to plot the following error
It's helpful to plot the joint following error and joint velocity
when tuning.

Note that if you use homing to index, you must connect the encoder
index enable signal to both motion and the PID component.

I've got a working config without Encoder input!
That link is very helpful. I'll be following it later today!
Thank you very much!