Axis direction parameter hall

Hello Experts !

First happy new year , Please I want to use an VFD to run the axis X . for this i would need to have in 7i77 output , one for X direction forward and one For X direction reverse .
I looked on the hall config but i could not find any Bool output that can be linked to this ,for the spindle yer there are a CW and CCW
but for the axis I couldn't find !!

Could you help me on this

It's unusual to use a VFD for an axis.
One way would be to use HAL components to check if the axis command is negative or not.

More information about your interface hardware and what your are doing would help for more precise ideas.

Chris M

Thank you for your reply . I m using a 5i25 with 7i77 . My aim is to use a vfd i the axis X. For the analog output i think that setting the pid to 0 to 10 volts can be done . So my issue is the hall syntax for.the command if negative or positif . I didnt find this hal component .could you please either show me where is listed on the hall config or write to me so i can add it to my hall .
I want to have 2 digital outputs for the two axis directions .
I already worked in a cnc machine that uses a vfd and it gives .
0.001 mm . The setup is special but the result is very positif .

Have a look at axis.X.pos−cmd
The sign denotes the direction being travelled.

This component I wrote a while ago shows how to determine the direction of movement on an axis. It was designed to display up and down LEDs in a GUI so it might need some modification but basically it does what you want by providing separate pins to show direction
forum.linuxcnc.org/plasma-laser/32657-th...-indicator-component .

Standard HAL components are great but if you know how to program in C, it is much more efficient to create dedicated components and that makes your HAL files easier to read.

Actually, I got it wrong in my earlier post. That technique used to work and then the internals changed so I wrote the component.

Thank you . But the X.pos-cmd is float and not a bit ?! I may be wrong .
Could you invest more

nkp has already shown the answer. Pass the PID output through an "abs" HAL component, then use the abs.0.sign output to control the direction pin.

akim wrote: Thank you . But the X.pos-cmd is float and not a bit ?! I may be wrong .
Could you invest more

As I said, it no longer works but when it did, I used the abs component as has been suggested with the PID output (which should already be attached to a signal in your Mesa config. something like