Accessing HAL pin from gcode

I have features = 12 enabled and the gcode loads ok however the resultant #1 = #[<_hal.mycomp.xoffset>] always evaluates to 0.000 even though the HAL component shows a non-zero value. I have seen where the hal pin needs to have a -f appended is this the case?

Hi wn007:

Based on your description, there really isn't a lot to go on. However if you check out the, “M codes”, particularly M62 – M68, that might be a nice place to start.

Have you read this...
forum.linuxcnc.org/forum/22-pyvcp/28826-...ariable?limitstart=0

Rick G

Yes, I have gone through that topic several times.

I am on 2.7.4

Here is the gcode that I am using. The strange thing is that when I load the ngc file from disk it actually executes the while loop within the oword subroutine immediately (while parsing). It appears to only update the HAL pin on the program load not while executing the gcode.

G20
G91
G94
G1 Z89.053 F10
G1 B8.0168 X9.03586959 F250
G1 W1.07238080 F15
G1 Y10.3500000000 F325
M64 P3
M65 P3
#1 = #<_hal[motion.analog-in-00]>
o<take_pics> call [#1]
M30

o<take_pics> sub
G91
#2 = .485
o100 do
#3 = #2 - #1
#4 = #3 / 8
G1 Y-.05 X#4 F50
G1 Y-.05 X#4 F50
G1 Y-.05 X#4 F50
G1 Y-.05 X#4 F50
G1 Y-.05 X#4 F50
G1 Y-.05 X#4 F50
G1 Y-.05 X#4 F50
M62 P3
G1 Y-.05 X#4 F50
M63 P3
#1 = #<_hal[motion.analog-in-00]>

o100 while [#1 NE 0]

What if you tried this.

I have tried the M66 E0 which in fact works, however it breaks blending so there is a pause between successive loops. We are attempting to eventually reach 300 to 400 IPM with no pauses / breaks in the execution. Thanks for the reply.

I'm not sure it can be done without breaking blending, because blending can't be calculated if the move is unknown.

You might be able to achieve your goal by using a slightly different approach. Could you do your math and check your analog pin in hal, then having hal set a motion.digital-in bit that then breaks your G-code loop? If you need to control the values of your points set them with an analog out, in the code but do the realtime testing in hal.

Yes, I did find in the docs where the inline HAL is evaluated once on load and should not be used for current values during execution.