THCAD-5 Reading negative Voltages

Hi, 
I wired up my THCAD-5  today 4.9Mohm on the negative Lead of the plasma rectifier output to the THC. 
Im using a Cebora PlasmaProf 52. i wired up positive input of the THCAD-5 to the rectifier output of the plasma cutter which had continuity to the clamp on the table for (which supposedly is on the positive voltage of the plasma cutter  ). 
I am getting readings from the THC but it is negative voltage. While cutting the negative voltage -3000 or so drops to -2600. (jumper set to 1/32) so the THC works somewhat without adjusting the settings...
But why am i getting negative voltage ? Should i just switch the cables at the rectifier to get positive voltage ? or is there a Setting to invert the voltage somewhere.
Appreciate the help 

Luc

Sounds like a scaling/setup issue

The input polarity is correct

You need this in your hall file. Change your encoder.01 to suit the encoder you are using. Likely .00

Hi, 
Thanks for the quick response im using PlasmaC currently.
I set up my encoder as follows:

# THC-5 ENCODER SETUP

setp hm2_7i96s.00.encoder.00.scale 1
setp hm2_7i96s.00.encoder.00.filter 1
setp hm2_7i96s.00.encoder.00.counter-mode 1

Since all of you say its not a wiring issue i will see which options work in the hal file mabye i need to change the scale to -1 as rodw pointed out. 
I will post once i get it to work

 

Hi, 
Had to leave town for a few days for work so i could not work on my machine. 
Setting the encoder scale to -1 worked, thanks a bunch