Control of second Z axis by input from paraport

Greetings all,

I'm a bit of a newb and have to date converted a old 3 axis Archdale mill and built a 3 axis router that both run on LinuxCNC. I have a commission to build a machine that will do V-carve routing on the outside of wooden barrels. The OD of these barrels are about 16" and can have a random out of roundness of about 1/2". My plan is to control the V-carve bit in a Y axis - Z axis configuration while the barrel is rotated via the B axis. Due to the random out of round nature of the barrel surface and the need to somewhat accurately control the depth of the V-carve cut , my plan was to have a separate stepper controlled by a sensor that follows the elevation of the barrel surface. This stepper will be used to raise and lower a secondary Z-axis stage that will be controlled by regular G-code that is used to carve the barrel graphics. I want to be able to feed digital input from the sensor to the parallel port and use those signals to control the stepper that will raise and lower the secondary Z-axis stage. Can anyone help me out or point me in the right direction as far as HAL commands to control the primary Z-axis stage? A.K.A If paraport pin 13 goes high the primary Z stepper turns one direction until pin 13 goes low and if pin 12 goes high then the primary stepper turns the other direction until pin 12 goes low.

TIA

Greg

You might want to look at Torch height control for a starting point.

Rick G

Thanks Rick for your suggestion.

I''ve been through all the THC stuff and have been getting lost in all the .hal and .ini files and have also been through the HAL, Intergrator, and Developer manuals but are still struggling. Bottom line is I just need to figure out how to output step and direction bits when one of the hardware input pins goes either high or low.