Disable cycle start / run button until conditions are met?

Hi all, I've searched for a while but can't find any info on how to do this, if there's a resource I missed please link me.

On my machine I have a few sensors for whether the operator has folded some fixtures away and I'd like to allow the machine to be on/jogging enabled etc but prevent starting a job if the sensors report that the fixtures are still out. How would I do this?

Basically I'd like to disable the start button until sensors A, B, and C report ok.

 

You can either physically add your sensors to your estop chain or you can build your estop chain in software with the estop-latch component. 

There is an example in the forum here under hal examples of using estop-latch but it only uses 1 estop but chaining them together is the way to solve this. 

Sorry, I should've been clearer; I don't want to estop the machine, i want the user to be able to jog the machine around and do all the normal manual things, I only want to disable starting an NC file.

It's more than just fixtures (it's about 7 sensors), it's also stuff like whether the door is shut - the user may need to move the machine with the door open, but shouldn't be able to start a job with the door open.

How would I do that?

On the phone so might wana double check this.
LinuxCNC has pins for
mode.is.auto
mode.is.manual
mode.is.mdi
Or similar, also has state pins, but Rod knows that much better.
Basicaly you would just need it to not go into auto mode, the rest seems ok from your explanation.

Hmm I only could imagine to play with the homed state. So unhome the machine if one of the sensors A,B or C is not ok, otherwise home the machine. Not ideal but I have no better idea.
 

Maybe you could link your fixture sensors to the estop chain in hal to have them trigger an estop UNLESS mode-is.manual is true.