Moving an axis to a particular distance using hal command.

Hi,

Problem: Need to move 4th axis to a certain distance (say 100mm) using hal command.

I am configuring a machine where I need to move my 4th axis to certain distance (say 100mm) and I am trying to do it on a particular sequence in my ladder logic.
When a particular switch is activated, I want my 4th axis to move to this distance and stop. I was thinking that it could be possible if I assign the distance value to the position command pin joint.3.motor-pos-cmd. But I was wrong in that. It was an output from LinuxCNC GUI (I hope so). I couldn't find any other input pin for assigning the position command.

Is there any option for moving an axis to a certain distance from hal command.?

Hardware: EC500_v5 with remora firmware.

I am a beginner to LinuxCNC. Kindly help me in this learning process.

Hope to get a response.

-Aravind. 

Just a stab in the dark, but maybe using hal to monitor the pin then activating an MDI command that runs certain gcode to move the axis/joint?
PyVCP panel can run MDI by clicking on buttons on screen, so just making that button controllable by physical switch should be doable.

Is there any other method in which I can move the axis to a particular distance from classicladder ladder logic.?

-Aravind

Does the movement need to occur in the middle of a running G-code program?

Is the distance to be moved always the same?

 

[ISSUE SOLVED]

Added a section in INI file for MDI command.

Now I got halui.mdi-command-00 under Pins > halui mdi_command-00 in HAL Configuration window which I could run by a true command. And I was able so net one output variable in classicladder to this pin and was able to move the axis for the required distance.

-Aravind.