Adjustment of feed override with a potentiometer

Hi! I need help in configuring my HAL file to adjust the feed override with a potentiometer. I upgraded a Bridgeport Interact 1 cnc mill. I have a 555 IC providing 5V "steps" to the encoder 04 pins of my Mesa 7i77 card. The signal looks good on my oscilloscope. The frequency from the 555 can be varied with the pot from 20Hz to 160Hz. I am using phase A only of encoder 04 connector (single ended). The ground wire is also connected. I tried using the MPG input 16 rather than the encoder 04, but it I didn't succeed. I also have a switch to enable feed override. When I turn on the switch, the cursor on the "axis" screen for feed override flickers back and forth quickly from 0 to 100 to 0. I change the scale for FO in my HAL for other values, but the cursor of FO will still moved quickly back and forth. My lines in my HAL file for feed override are:

net fo_enable <= hm2_5i25.0.7i77.0.0.input-15
net fo_count <= hm2_5i25.0.encoder.04.count
setp halui.feed-override.direct-value false
setp halui.feed-override.scale 1
net fo_enable => halui.feed-override.count-enable
net fo_count => halui.feed-override.counts

I read several posts on the subject, but I couldn't figure out what I am doing wrong. Any help is welcome!

this is not what you are asking, but the first few (3?) inputs on 7i77 can be set to analog input mode with this command:

That is correct, the 7I77 MPG inputs have no counter mode, and only work with quadrature inputs.

1. The encoder will not count with just 1 input unless you select counter mode
2. Why don't you use the 7I77 analog inputs?

Thanks for the information. It's much appreciated! I will try using the 7i77 analog inputs, with the addition of the command loadrt hm2_pci config=" sserial_port_0=200xxxxx" as mentioned by fixer.

I connected the feed override potentiometer to the 7i77 analog input input 0 (pin 1, TB8) and it works perfectly!

Here are the lines of my HAL fine in case someone runs into the same issue:

# added to convert fload to s32 for feed override:
loadrt conv_float_s32 count=0
addf conv-float-s32.0 servo-thread

# ---potentiometer wiper connected to analog pin input 0---
# ---fo_count converted from float to s32 into fo_fount_conv

net fo_count <= hm2_5i25.0.7i77.0.0.analogin0 conv-float-s32.0.in
net fo_count_conv conv-float-s32.0.out

# ---connect converted value of analog input 0 to feed override counts---

setp halui.feed-override.direct-value false
setp halui.feed-override.scale 0.1
net fo_count_conv => halui.feed-override.counts

Thanks again for your help!