THC doesent work when G code is running

while doing the first tests on my machine I noticed that THC doesnt work when the machine is running G code
I looked around and did some tests and it does work and move the z axis when I start a manual cut with f9 and jog with the arrow keys

QtplasmaC is getting arc voltage and arc ok signals 
the G code im testing is the metric wrench and things from the conversational panel
the THC enabled light turns on but not the active light
it looks like the machine is getting up to the feed speed 

how should i troubleshoot this and am I missing something obvious?

Have you enabled the THC in the GUI?

THC is enabled in the GUI and mesh mode is turned off

left the config attached in case it might be of any use

I don't see anything in the hal  files that reference the THC or plasma voltage or
source for plasma voltage information at all.

There is 
net plasmac:arc-voltage-in <=  lcec.0.3.ain-0-val
so the voltage is provided by an ethercat analog input
and I see the GUI settings of
Arc Voltage Offset = 0.0
Arc Voltage Scale = 300.0

How do you scale the input back to volts?
Do you see a Voltage being displayed?
What I'm seeing is you are multiplying the input value by 300 which does not sound right. 
I would have thought you would be using the voltage divider factor from your plasma cutter. eg if 20:1 you'd multiply by 20.
The other approach would be to scale the voltage outside of QTplasmac and use a scale of 1 which I have used before.
Need to get your voltage correct before looking at thc

Im using a beckhoff 3102 +-10v analog input so im dividing the arc voltage 30:1 inside the powermax 65, and after the first tests with a bench power supply I realized that the beckhoff module outputs a float value between -1 and +1, given the range I assumed it relates the voltage and the float output value 10:1, so in qtplasmac i combined the two ratios to be 300:1 the cut voltage appears to display right in the tests i have done so far, 200 something volts at ark start and stabilizing at about 130V and that agrees with hyperterm's tables for the parameters im using

edit:
and as I said before thc is working fine when doing a manual cut with the jog keys
 

voltages sound about right. Nice to know ethercat is so simple to install for plasma machines.

I'm a bit rusty, it can be a bit cantankerous  on non standard setups, Check the thc is not disabled in the gcode which sounds a likely place to look

I looked at the code I was using and the thc enable gcode is there, the thc enabled light is on, but not the thc active light thats what confuses me, what are the requirements for it to activate?