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50:1 would be OK with with thcad 5 volt scale.
on 10v scale, Use 20:1 which is 200 volt full scale. That will be more accurate. It will probably go off that scale briefly when piercing but  it won't matter as we don't care about the voltage until it settles back to cut voltage of about 130 volts. The THCAD can handle the over voltage.

Hi Rodw,

My automation card divider is 50:1 by default but can be set to 80:1, 40:1, 30:1, 20:1, and 16.7:1. Would you still suggest the 20:1 or would the default 50:1 work just as well?

SwitchWitch wrote:

 As you mentioned before usb to rs485 is an option, I will go that way until I will be able to spend the next bucks for an ethercat VFD.

I think once you get that going, you will find it works so well, you will never go to an ethercat VFD.
Does Optidrive have a separate ethercat interface module for your VFD? A number of manufacturers do.

You don't need a relay as your card has 2 amp relays built in to the high current outputs, Use one for the torch on. Adding a relay would just add an additional failure point and add some lag into the signal.
I think your plasma has the same divider as the TD  A120 I had. In which case, use a 30:1 divider without any scaling resistors on the THCAD's 10 volt scale. If you do have a 20:1 divider (I didn't)  you could use that. set the frequency divider to 1/32 and scale the sticker frequency by the same amount when configuring qtplasmac
You do need to use a pull down resistor on the ArcOK input which is discussed in the QTP manual.

oops here is the new file.

Here is a slightly different file to try. replace the one I gave before.
I think there still will be a focus problem if you click the gcode display then spacebar.
But clicking the window or graphics display should refocus so space bar works again.

If you can confirm these things, I will look further into the gcode display problem.

Focus problems are always a pain!
Thanks

Hi,

I'm converting a Crossfire Pro to LinuxCNC using a Mesa 7i95t and THCAD2.  I have the automation interface card in the cutmaster 60i so it has the torch start/stop, voltage divider, ok to move, and ohmic sensing on the CPC connector.  I'm still waiting for the THCAD2 to come in but the wiring for it seems pretty straight forward.  I've attached the wiring diagram from the service manual and I'm not quite sure if I can just wire the start/stop directly to a 7i95t output or if I need to use a relay.  If I understand the qtplasmac docs I should be able to connect the ok to move directly to an input but may need a resistor if the current draw isn't enough.  I may hook up ohmic later but would I need another THCAD2 for it as well?

Thanks,

Kevin

You lucky ....
You are welcomed, always.

got one ...

thanks

I wanted to say that there is a new Modbus interface: hm2_modbus
available for all Mesa cards, and that fixes a lot of the issues with mesa-modbus.
hm2_modbus needs the latest snapshot of 2.9.4 or master. and may require
a firmware upgrade to at least V2 PktUART.

It adds the ability to have multiple devices on the same RS-485 interface,
device initialization/setup code that only runs once, plus many bug fixes.
Its been running a 25IOC32_PNP for a more than a week now with 0 issues.

The configuration file has a different format (XML) than mesa-modbus.
This format is documented in the mesambccc man page ( mesambccc is
the hm2_modbus configuration file compiler)