Need help setting up HAL files for MESA THCAD10

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11 Apr 2021 12:44 #205634 by CCharles
I saw they were dumping support just yesterday actually. I have used Visual Studio a little in the past. I may give that a try.

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11 Apr 2021 17:27 #205658 by CCharles
I am getting a velocity when watching the encoder velocity. It is fluctuating as well as is a negative number. Is it suppose to be negative?

If I set the Scale and the Offset using the online calculator I am getting negative volts on the Plasmac display as well.

Also, I assume it should stay at 0 volts and fluctuate by tens or more and that is noise in the system. Is this what the low pass filter is used for?

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11 Apr 2021 21:58 #205680 by andypugh

I saw they were dumping support just yesterday actually. I have used Visual Studio a little in the past. I may give that a try.


I use Geany on everything. It's closer to a text editor than an IDE, but it can, for example, take you to the definition of a thing if the defining file is open.

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12 Apr 2021 01:21 #205690 by PCW
If its negative, change the sign of the encoder scale
(the -1 scale assumes Mesa hardware where the default
encoder direction is negative when the B input is unconnected)

Some noise is due to the the resolution of the voltage reading
which is limited by the base thread rate in parallel port systems,
but with low pass filtering you can increase the resolution at the
expense of control bandwidth. (and typically, control bandwidth
will be more limited by Z axis acceleration than the electronics)

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12 Apr 2021 03:24 #205694 by rodw
One of my brutal learnings about the Everlast 50s is that its resistors in the voltage divider are claimed by the THCAD. So be sure to set the plasma cutter up as 16:1 but set up the THCAD and Plasmac in Linuxcnc up at 24:1 otherwise your voltages will be reported as low.

Also, they seem sensitive to noise in the voltage signal. I found most of this was a 50 Hz oscilliation coming via the mains earth wire.

You can view this in halscope.

Be sure to install a EMI filter on the mains input to your control box and fully implement the Hypertherm grounding recommendations. If thats not enough, I'd suggest you try with the cabinet frame ground and any shield on your interconnect cable is NOT connected to the THCAD.

Also, another brutal learning is the ArcOK relay is prone to oxidisation which will result in intermittent or failed operation of the ArcOK signal.

If you were using a Mesa card, its mandatory that you connect a 100 ohm, 10 W pull down resistor from the ArcOK input to field power ground (if at 24V). I'm not sure what is the recommended value on a Parallel port card. You would need to do some maths to determine the required value. (Unless your parallel port is not a high impedance circuit.)

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12 Apr 2021 04:14 #205696 by phillc54

If you were using a Mesa card, its mandatory that you connect a 100 ohm, 10 W pull down resistor from the ArcOK input to field power ground (if at 24V).

That is incorrect, a resistor is not mandatory, it is an option.

Another option using a capacitor:
forum.linuxcnc.org/plasmac/40819-arc-ok-...fire?start=50#191678

If you really wanted to use a resistor then it would be prudent to find the specifications of the relay and find the correct value resistor to use.

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12 Apr 2021 04:29 #205697 by rodw
For this machine its not an option.

Doing something to ensure the ArcOK is reliable is mandatory on the Everlast 50s the OP has.
Myself and littlesparky can both attest to this.

And yes, as I said, the OP needs to do his own homework and calculations to suit the voltages and circuit impedance. But if its not addressed, problems are likely to follow very soon after he gets up and running.

Everyone seems to have latched onto the use of a capacitor mentioned by PCW as the best way to go but if you read his post, he does not recommend one over the other

The required contact wetting current is dependent on switched voltage.
For example for one manufacturers silver contact relay the minimum wetting
current was 160 mA at 5V but just 26 mA at 30 VDC. The significant parameter
is the energy available to clean the contacts.

Another way of providing wetting current without any added power dissipation
is to parallel the contacts with a small film capacitor circuit (say 1 uF
capacitor for a 24V circuit) This provides a high surge current on contact
closure but the total energy is limited (~.03 mJ)

forum.linuxcnc.org/plasmac/40819-arc-ok-...fire?start=50#191678

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12 Apr 2021 04:40 #205698 by phillc54

For this machine its not an option.

Doing something to ensure the ArcOK is reliable is mandatory on the Everlast 50s the OP has.
Myself and littlesparky can both attest to this.

And yes, as I said, the OP needs to do his own homework and calculations to suit the voltages and circuit impedance. But if its not addressed, problems are likely to follow very soon after he gets up and running.

Everyone seems to have latched onto the use of a capacitor mentioned by PCW as the best way to go but if you read his post, he does not recommend one over the other


If you read my post you will see that I was pointing out that a resistor is not mandatory which is what you stated in your earlier post.

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12 Apr 2021 18:24 #205726 by CCharles
Ok thanks. I will try changing that this weekend when I am back at the machine.

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12 Apr 2021 18:30 #205727 by CCharles
I was actual just about to ask about the divider ratio on my Everlast. I have come across your post about this before. I have been using the divider ratio of 24:1 for my calculations, but it didnt seem to be right on. Got me wondering if Everlast changed that since you worked with that machine.

I did look at the Halscope, but admit that I am not used to looking at things like that. I couldnt really tell what I was looking at.

I did pick up a power strip from an IT guy at work today used for the servers. He said it has EMI filtering built in and was going to try using that.

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