Hello everybody!

I hope you can help me. I already spent days on my problem... We have a *UNIMAT 
CNC 3-Axis Mill* <http://www.thecooltool.com/en/products/unimat-cnc/> which 
was controlled by a computer. The CNC is part of an educational production 
demonstrator, which itself is controlled by a PLC. Having a rather space 
consuming pc and another person around (to start a milling process) is not 
very desirable. We brought a mini-computer from the same manufactor. It is 
basically a BeagleBone Black with a custom parallel port cape. It runs 
under Xenomai. The setting runs quite nice, you can start AXIS via USB 
connection. But we realized, that we still need a person with a seperate 
computer or laptop to start the milling. Our target is to use the PLC to 
trigger the milling procedure. There will be a seperate electrical 
interface which provides voltage level shifting and isolation between 
BeagleBoard and PLC.

For the start, I looked up the One Button Run/Resume example. I decided to 
use the pin 46 of port 8 on the BeagleBoard for this function. I inserted 
*bb_gpio.p8.in-46* and added the pin number *846* to

# load low-level drivers
loadrt hal_bb_gpio output_pins=826,827,923,926,930 
input_pins=807,810,814,817,818,819,846,912,914,915,916,917,918,924,941

in one of the .hal files. I also added *HALUI = halui* to the *[HAL]* 
section in the .ini file. In another file (.bbio), which seems to be 
processed at statup, I changed the line

P8_46 default

to

P8_46 in

To use the pin as input, I disabled the automatically loaded HDMI-cape 
configuration in uEnv.txt and configured the pin as input with

echo 71 > /sys/class/gpio/export
echo in > /sys/class/gpio/gpio71/direction

This runs on each system start-up.

When I apply 3.3 Volts to pin P8.46, I can read a locial 1 using *cat 
/sys/class/gpio/gpio71/value*. So far, so good. But when I start AXIS and 
open the Hal Meter, select bb_gpio.p8.in-46, it always returns FALSE 
although the terminal running next to it, returns a logical 1.

Am I doing something wrong or forget any step? Do you have any suggestens 
for me?

Additional information
uname -a returns
Linux sandybox 3.8.13-xenomai-r70 #1 Fri Jan 23 01:35:45 UTC 2015 armv7l 
GNU/Linux

I should also note that I just started gaining experience with Linux in 
general.

Thank you very much
Bastian

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