Random arc signal lost

snowgoer540 wrote:

phillc54 wrote:

Something else you could experiment with in <machine-name>-connections.hal

Unlink the plasmac Arc OK input .
Add an extra debounce component.
Net the Arc OK signal from the Mesa card to the debounce input and the debounce output to PlasmaC Arc OK .

I really need to start writing things down. I had this though on the way to work this morning! I actually thought "I wonder if the Arc-OK is de-bounced". I think the Hypertherm closes a set of dry contacts, so it could be that there needs to be a small debounce before things get under way. Does that mean this stuff is really starting to make sense?!

Ok, I just looked, the Hypertherm definitely closes dry contacts. I wonder if that's the problem?

Could you offset the debounce delay by then making your pierce delay a bit shorter, or maybe it really doesnt matter that much?

phillc54 wrote:

snowgoer540 wrote:

phillc54 wrote:

Something else you could experiment with in <machine-name>-connections.hal

Unlink the plasmac Arc OK input .
Add an extra debounce component.
Net the Arc OK signal from the Mesa card to the debounce input and the debounce output to PlasmaC Arc OK .

I really need to start writing things down. I had this though on the way to work this morning! I actually thought "I wonder if the Arc-OK is de-bounced". I think the Hypertherm closes a set of dry contacts, so it could be that there needs to be a small debounce before things get under way. Does that mean this stuff is really starting to make sense?!

Yes

Ok, I just looked, the Hypertherm definitely closes dry contacts. I wonder if that's the problem?

Could you offset the debounce delay by then making your pierce delay a bit shorter, or maybe it really doesnt matter that much?

Probably not required, each debounce "unit" in a servo thread is normally only 1mS

loadrt  debounce                cfg=4
#net plasmac:arc-ok-in hm2_7i96.0.gpio.010.in => plasmac.arc-ok-in
net plasmac:arc-ok-in hm2_7i96.0.gpio.010.in => debounce.0.3.in
net plasmac:arc-debounce debounce.0.3.out => plasmac.arc-ok-in

snowgoer540 wrote:

gs Would that look like this:

loadrt  debounce                cfg=4
#net plasmac:arc-ok-in hm2_7i96.0.gpio.010.in => plasmac.arc-ok-in
net plasmac:arc-ok-in hm2_7i96.0.gpio.010.in => debounce.0.3.in
net plasmac:arc-debounce debounce.0.3.out => plasmac.arc-ok-in

phillc54 wrote:

snowgoer540 wrote:

gs Would that look like this:

loadrt  debounce                cfg=4
#net plasmac:arc-ok-in hm2_7i96.0.gpio.010.in => plasmac.arc-ok-in
net plasmac:arc-ok-in hm2_7i96.0.gpio.010.in => debounce.0.3.in
net plasmac:arc-debounce debounce.0.3.out => plasmac.arc-ok-in

That looks OK to my bloodshot eyes

rodw wrote:

So the solution is to add a pull down resistor to the ArcOK input. This resistor has to be sized to ensure the minimum current is exceeded and can also handle the power in the circuit (Watts). In my case, I was able to locate the relay in the Everlast and track down the data sheet. The minimum current rating was 100 mA. My advisory panel crunched some numbers and announced that I should use a 1K, 1 watt resistor from the input to my 24V field power ground. They said to keep the resistor up in the air as it could get very hot!

The isolated inputs use opto-isolators with a 4.7K input series resistance. This results in an approximate current draw of 5 mA at 24V. The inputs will operate with +-4V to +-36V signals relative to input common. Isolated inputs are relatively slow and not suited for signals faster than about 5 KHz. For sinking type inputs, the input common pin is grounded and a +4 to +36V signal is applied to the input pins to activate the input. For sourcing type inputs, the input common is connected to +5 to +36V and the input pins are grounded to activate an input.

The 7I76E field inputs have a nominal input resistance of 20K Ohms to field power ground. 7I76E inputs sense positive input voltages above a preset threshold. For best general purpose use, default input threshold is 50% of the field power supply voltage with 10% hysteresis. That is with a 24V field voltage an input must be brought to 60% of 24V = 14.4V to be sensed as high and then brought to 40% of 24V = 9.6V to be sensed as low. These accurate thresholds and hysteresis allow high speed field signal detection while maintaining excellent noise immunity.