THC for Hypertherm 45XP based on DT-115 / LM393 comparator

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22 Oct 2020 10:34 #186889 by radek_marko
How does this board pick the right hight for material from the PlasmaC panel?
On the product panel I can see the pierce height, cut height etc and I do not see any info re ARC current or ARC voltage.

I'm guessing it does work auto-magically, but what's the source of the magic?

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22 Oct 2020 15:45 #186906 by rodw
The settings for current and voltage are in the plasmac materials file (when you create it.). All of that is left to Linuxcnc. Most of us auto sample the voltage so there is no need to really worry about the voltage. Plasmac can talk via rs485 to the 45XP to set current and pressure.

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22 Oct 2020 19:57 #186926 by radek_marko
OK, after several tests I'm ditching the initial plan of using DT-115 / LM393 and will buy proper THC...

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30 Oct 2020 20:27 #187829 by radek_marko
tommylight

From THCAD FO+ to parallel port input, set that input as the encoder A input in hal.


My board arrived and I've connected both sides of the board but I'm struggling with HAL.
My FO+ wire is connected to LPT2 IN PIN 15 (parport.1.pin-15-in), Hypertherm is set to 20:1 voltage divider.

I would appreciate some help or even an example of HAL file with THCAD-10 connected.

I have added my plasma_connections.hal below. I've removed existing UP/DOWN move inpus from my non-functioning DT-115 THC.
# net plasmac:move-up parport.1.pin-13-in => plasmac.move-up
# net plasmac:move-down parport.1.pin-12-in => plasmac.move-down

I have the following questions:
1. Where do I need to connect FO- signal from THCAD-10 board (currently not connected)
2. I was expecting to find ENCODER A commented out in hall file, but I do not see it - where can I find example?
# Keep your plasmac i/o connections here to prevent them from
# being overwritten by updates or pncconf/stepconf changes

# Other customisations may be placed here as well
# This file is built by the configurator in your configuration directory

#***** debounce for the float switch *****
# the lower the delay here the better
# each 1 is a 0.001mm (0.00004") increase in probed height result
loadrt  debounce                cfg=3
setp    debounce.0.delay        5
addf    debounce.0              servo-thread

#***** arc voltage lowpass cutoff frequency *****
#***** change to the cutoff frequency you require *****
setp plasmac.lowpass-frequency 0

#***** the joint associated with the Z axis *****
net plasmac:axis-position joint.3.pos-fb => plasmac.axis-z-position

net plasmac:arc-ok-in parport.1.pin-11-in-not => plasmac.arc-ok-in
net plasmac:float-switch parport.1.pin-10-in => debounce.0.0.in
# net plasmac:breakaway {YOUR BREAKAWAY PIN} => debounce.0.1.in
# net plasmac:ohmic-probe {YOUR OHMIC PROBE PIN} => debounce.0.2.in
# net plasmac:ohmic-enable plasmac.ohmic-enable  => {YOUR OHMIC ENABLE PIN}
net plasmac:torch-on => parport.1.pin-17-out
# net plasmac:move-up parport.1.pin-13-in => plasmac.move-up
# net plasmac:move-down parport.1.pin-12-in => plasmac.move-down

# a 1 here allows multiple tools to be used
# gcode M3 S1 needs to be changed to:
# M3 $0 S1 for the plasma torch
# M3 $1 S1 for the scribe
# M3 $2 S1 for spotting
setp plasmac.multi-tool 0
# net plasmac:scribe-arm plasmac.scribe-arm => ***YOUR_SCRIBE_ARMING_OUTPUT***
# net plasmac:scribe-on  plasmac.scribe-on  => ***YOUR_SCRIBE_ON_OUTPUT***
Attachments:

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30 Oct 2020 22:05 - 30 Oct 2020 22:10 #187842 by tommylight
The hal file (also can be done in the machinename_connections.hal) needs to have :
- a base period set as low as it can go without having latency error displayed
- based on that value and the max steps the port can read a calculated decision can be made to use the 1/32 or 1/64 or 1/128 divider on THCAD
- loadrt for the encoder
- addf for the encoder
- Encoder mode
- encoder phase A wired in hal to parallel port input
Attached is a working configuration, but the important parts are in the torchud.hal file.
Attachments:
Last edit: 30 Oct 2020 22:10 by tommylight. Reason: attachment
The following user(s) said Thank You: radek_marko

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30 Oct 2020 22:05 #187843 by PCW
For use with a parallel port, FO- is left unconnected

You need to load an encoder component to use the THCAD's frequency output
with a parallel port

for example:

loadrt encoder
addf encoder.update-counters base-thread
addf encoder.capture-position servo-thread
setp encoder.N.counter-mode true
net enca encoder.N.phase-A parport.1.pin-15-in
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30 Oct 2020 22:40 #187847 by radek_marko
Tommylight and PCW - Thank you very much. I will test it tomorrow.

I was searching for the phrase ENCODER and found the following in the documentation:

The limit is in the range of 10KHz to 50KHz, depending on the computer speed and other factors

Then I have spotted the sticker at the bottom of THCAD board

and now with Tommylight's comment

based on that value and the max steps the port can read a calculated decision can be made to use the 1/32 or 1/64 or 1/128 divider on THCAD


It makes perfect sense! I need to find which parameter in the config reflects F/32, F/64 or F/128.

So, I will modify my .ini file to add new torchud.hal - a copy of Tommylight's. In the hal file I will change the input port.
loadrt torchud
loadrt encoder num_chan=1
addf encoder.update-counters base-thread
addf encoder.capture-position servo-thread
addf torchud servo-thread
net enc-phase-a <= [b]parport.1.pin-15-in[/b] [strike][b]parport.0.pin-13-in[/b][/strike]

#setp encoder.0.position-scale 300
setp encoder.0.counter-mode 1

net enc-phase-a encoder.0.phase-A

net thc-encoder-vel encoder.0.velocity => torchud.encoder-in

net TorchOn torchud.enable
setp torchud.voltage-offset 1880

#setp torchud.voltage-scale 0.01132877
setp torchud.voltage-scale 0.022855

#setp torchud.setpoint 5
#setp torchud.tolerance 2
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30 Oct 2020 23:34 #187850 by tommylight

radek_marko wrote: So, I will modify my .ini file to add new torchud.hal - a copy of Tommylight's. In the hal file I will change the input port.
Final version should look like this:

loadrt motmod base_period_nsec=100000
loadrt encoder num_chan=1
addf encoder.update-counters base-thread
addf encoder.capture-position servo-thread
net enc-phase-a <= parport.1.pin-15-in
setp encoder.0.counter-mode 1
net enc-phase-a encoder.0.phase-A

And the
encoder.0.velocity
has to be added into PlasmaC configurator when setting it up.

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31 Oct 2020 10:29 #187881 by radek_marko
Tommylight - I need your help again...

I'm trying to get my head around voltage-offset and voltage-scale.

I've created my calculation for everyone to use if required: docs.google.com/spreadsheets/d/1dGBwp7ia...UeY/edit?usp=sharing



If I apply frequency divider as F/64 then I'm getting voltage-offset close to one from your config file, but my voltage-scale is way off.

I'm guessing your voltage divider at plasma output must be different than mine (I'm using 1:20).

Please let me know if my logic and calculations are correct.
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31 Oct 2020 10:37 #187883 by phillc54
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