Bench testing Mesa THCAD
08 Jan 2017 01:21 #85441
by rodw
Bench testing Mesa THCAD was created by rodw
I've been setting up my THC using Mesa 7i767 and a THCAD-10. I have not attached a plasma yet but have been doing some tests.
I've got most of the THC signals working eg.
arc-ok - using a switch to +24v
torch-on - Turns on a temporary light attached to the torch on relay when M3 is sent
enable - I attached this to an unused input pin-not and its working
encoder-vel - Counts away merrilly
current-vel - shows speed on Z axis in metres per second that agrees with a gcode S command in mm/min
But I figured once I got this far I should be able to see the volts output.
I stole some 5v poser from a stepper input and put -5v to THCAD IN- and then ran the +5v through a 100k pot to THCAD +IN
This is giving me a voltage range of 2.5v to 5.0V on the THCAD 10 volt range.
I'm not seeing anything in HAL Configuration. DO I need to attach the THCAD plasma input side to ground?
Here is my HAL stuff
Any help would be appreciated.
I've got most of the THC signals working eg.
arc-ok - using a switch to +24v
torch-on - Turns on a temporary light attached to the torch on relay when M3 is sent
enable - I attached this to an unused input pin-not and its working
encoder-vel - Counts away merrilly
current-vel - shows speed on Z axis in metres per second that agrees with a gcode S command in mm/min
But I figured once I got this far I should be able to see the volts output.
I stole some 5v poser from a stepper input and put -5v to THCAD IN- and then ran the +5v through a 100k pot to THCAD +IN
This is giving me a voltage range of 2.5v to 5.0V on the THCAD 10 volt range.
I'm not seeing anything in HAL Configuration. DO I need to attach the THCAD plasma input side to ground?
Here is my HAL stuff
# --- TOUCH OFF ---
net torch-probe motion.probe-input <= hm2_7i76e.0.7i76.0.0.input-09-not
# --- THC - TORCH HEIGHT CONTROLLER ---
# thc calibration data 0v = 122.9 kHz (122900), 10v = 925.7 kHz (925700)
# freq(x) = 122900 + 80280 * V
# so at 10V, 925700 = 122900 + (80280 * 10)
# 1/80280 = 0.000012456
setp thc.vel-scale 0.000012456
setp thc.scale-offset 122900
setp thc.velocity-tol 1.0
setp thc.voltage-tol 1.0
#This might need to be increased
setp thc.correction-vel 0.00001
setp hm2_7i76e.0.encoder.00.counter-mode 1
net thc-encoder-vel hm2_7i76e.0.encoder.00.velocity => thc.encoder-vel
net thc-current-vel thc.current-vel <= motion.current-vel
net thc-requested-vel thc.requested-vel <= motion.requested-vel
net spindle-on => thc.torch-on
# starts the motion when the plasma arc has transfered to the work
net start-motion-input thc.arc-ok <= motion.digital-in-00 <= hm2_7i76e.0.7i76.0.0.input-10
#enable THC just for TESTING
net thc-enable thc.enable <= hm2_7i76e.0.7i76.0.0.input-31-not
#unused THC inputs
#net thc.volts-requested
#net thc.vel-tol
#thc.z-pos-in
# THC outputs below
#net thc.z-pos-out
#net thc.z-fb-out
#net thc.volts
#net thc.vel-status
#net thc.offset-value
# --- ARC OK OUTPUT (to LED) ---
net start-motion-input => hm2_7i76e.0.7i76.0.0.output-03Any help would be appreciated.
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08 Jan 2017 03:38 - 08 Jan 2017 03:39 #85447
by rodw
Replied by rodw on topic Bench testing Mesa THCAD
I worked this out. The wiring was correct. I had the THCAD frequency set on the board to be 1/32. My scale and offset config needed to be:
The voltage output in HAL now seems to be remarkably accurate!
# --- THC - TORCH HEIGHT CONTROLLER ---
# thc calibration data 0v = 122.9 kHz (122900), 10v = 925.7 kHz (925700)
# so at 10V: 925700 = 122900 + (80280 * 10)
# but we are using 1/32 divider on THC board
# 1/32: input 0v = 3840.625, 10v = 28928.125
# 1/32 at 10v: 28928.125 = 3840.625 + (2508.75 * 10)
# 1/32 scale = 1/2508.75 = 0.000398605
setp thc.vel-scale 0.000398605
setp thc.scale-offset 3840.625The voltage output in HAL now seems to be remarkably accurate!
Last edit: 08 Jan 2017 03:39 by rodw.
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