Encoder for rigid tapping

Hi,
I have a 50p/r encoder with A, B & Z. It threads perfect and can thread at 1000rpm no hassles. I am trying to do rigid tapping, but when I use G33.1, it taps to the right depth, but when the chuck reverses, the tap goes in more and not out. Its like the stepper is not being told to reverse direction. 
In my HAL file I have the three inputs setup (net spindle-phase-a encoder.0-phase-A) etc, I have the scale set to 50 and encoder mode set to 1. When I turn the chuck by hand, the position in HAL view rises by 1 for every 1 revolution of the chuck, but if I turn the chuck in the opposite direction, it carries on increasing and not count down. Is this correct? My encoder is an incremental Omron E6B2-CWZ6C. I am using a prallel port BOB (blue). Nema32 stepper motors and can control my spindle speed via the VFD (Bosch)

Any help is greatly appreciated.

Sounds like you have the encoder component set to counter mode
rather than quadrature mode (counter mode set to 1 rather than 0)

( another hint is your scaling, a 50 PPR encoder is 200 counts/turn
in 4x quadrature )

man encoder
 

Aaah. Awesome. Thank you. I shall try this tomorrow and see how it goes. I will let you know once I have changed the settings.

I did as you suggested. Many thanks. It worked a dream and I can still thread at 1000rpm. Going to sort my motor slow down speed as its currently two revolutions. So i have modified my ngc file for not to account for this. Many thanks again