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Somewhat of a novice here but like you it has been several years since my last retrofit/build of a LinuxCNC machine. The last machine built was back in 2020 and the pi platform was not really a good option then. Currently I just retrofitted a full size industrial CNC router and I am using the pi5 8GB with a Mesa 7i96s. So far it has been flawless and totally stable. My motivation for using the pi is basically downloading the image and go, other than a couple of minor tweaks to the OS (my preferences) it just runs out of the box. Using the pi I don't have to worry about finding another PC that would work in the event of a hardware failure and the fact that I can make multiple super cheap fully operating copies of the OS on a SD card cannot be beat. The machine that I just retrofitted is going to be used in a production environment and will need to be totally reliable day in and day out.

about the VFD, it depends on the type,
i have only a hy_vfd and no real examples, what kind of VFD you have ?
is it realy modbus conform or like the hy_vfd a modbus like protocol ?

The new PR is up, this fixes everything, i will post some pictures later
Edit:
Still got a few kinks to iron out, probably tomorrow for finalized PR

Maybe reset the encoder count on each index pulse? Then it would not count to such high numbers. But this will break the speed output of your ddt (I think). Does the EL5151 not have an encoder velocity output? I just used a similar Beckhoff part recently but can't remember, I don't think I used or needed velocity (speed) feedback in that project.

there are an buildin watchdog, it will disable the pwm/stepdir output if the connection is lost.
you can also set a chain of 'modifiers' to each pin (plugin -> Pins -> Modifiers) like delay, debounce, ... and 'onerror'.
The 'onerror' modifier hold the pin to low or high if connection is lost.

You can also use the 'chargepump' hal-component (www.linuxcnc.org/docs/html/man/man9/charge_pump.9.html) to control a master power relay.

Ok, so I think I understand what I should do. Using the StepperOnline Motion Studio software, I change the ENA polarity from high to low so no input is disabled and 5V input enables the motors. Additionally, I can switch the ALM polarity from low (default) to high and take that input in as inverse. Basically like a NC estop. For the wiring on the ENA, can I daisy chain them together? Also for the ALM, can I run those in series with the GND coming into the first driver and the last driver returning the GND back to the controller, with 24V as the input common?

yes this is a requirement now. nonstandard modules require a virtual environment (venv) in a folder. Google python venv

Pid maxoutput limits in the positive and negative direction. So, you can set maxoutput to 1.0 and it will limit the output in the range of 1.0 to -1.0

I'm not sure what it would take to prevent windup below 0.

For what its worth, one thing that has bit me in the past in trying to tune PID and lots of troubles with windup: slow vfd accel/decel. If the PID is tuned to respond faster than the ramp time of the VFD, that'll wind it up.

Also, a hal limit1 component might be in order to prevent sending a negative voltage to the vfd analog input, some kinds smoke when they get negative signals.

Bob has 5v using usb.
I'm only working with 5v now to get step/dir outputs working.
I will connect the 12v supply to run the spindle.

I've started wiring and testing my custom RIO board and everything is looking good so far.

Is there any option to have a watchdog on the outputs? So if the computer crashes or loses connection the outputs will turn off?

Also are there any examples anywhere of controlling a spindle VFD over modbus with RIO?

This can be done with 5 7I84U outputs and 6 7I84U inputs in conjunction
with the matrix_kb component

If you expect to press more than one switch at a time
you need to add one diode per switch

I'm pretty sure there are examples of this on the forum so a
search for "7i84" and "matrix" might find something...

Hello Folks, 

I searched, but not much came about multiplexing the IO on a 7I84U or other mesa card. My panel will have 28 push buttons, 3 pots and one MPG. I could wire everything to the 7I84U, but with a 5x6 matrix I can mux all the switches, saving IOs. 

How can this be done? Examples would be much appreciated.

Greetings  

Also note that the pre-installed firmware on a 7I97T fully supports the standard analog and digital I/O
You typically only need different firmware if you have an added parallel daughtercard

Analog output problems are most likely a hal file or tuning/polarity issue
 

sure it does support .ngc

my s-curve blending is comparable to the current TP, there is some loss, but it is unavoidable, but not in mills or more range.