inhibit Machine turning on

How can I inhibit turning on the machine unless certain inputs are true?

I have certain inputs that need to be true to be able to turn on the machine re: safety ropes, thermo switches, air pressure.

These are important to the machine operation and should not be able to turn on the machine if they are tripped.

Should I just put them in the e-stop chain?

tommylight wrote:

I would wire that to separate inputs that would in turn halt motion and display an alarm. Search the forum, there are several threads that mention alarms and how to set them up, like drive fault alarm or similar.

OK, thanks. The machine has them all wired in parrallel through the e-stop with a latching pushbutton to start the machine and a stop button. Problem is you wont know what was tripped.

I'll try it your way Tommy. Thanks.

For my air pressure input I have
You will have to change the PPMC portion to your hardware, and the in-not/in to match the state of your switch

This creates a "motion inhibit" which will prevent the machine from turning on
There is a way to

loadrt message names = air-alarm messages = "LOW AIR PRESSURE"
addf air-alarm servo-thread

I have not gotten the message to work correctly yet, but I have not spent much time on it. The motion inhibit does work. I would only have the things critical to safety in the safety chain. Unless air is critical to the safety chain I would just use it as the part of the motion inhibit.

As you have mentioned in your initial message it is good idea to wire your safety switches in series with the estop.
For annunciation and to facilitate troubleshooting wire the spare contact in the safety switches (low pressure, pulled safety rope,...) to the inputs of the mesa card and use HAL to connect the switches to your alarm on the screen.
Note: Make sure to use the field power from you mesa card to wire up the new contacts.
See attached diagram

Somewhere I saw an example of a HAL logic command that fed 4 inputs into the e-stop circuit. All all of the inputs had to be OK or an estop would trigger. I've done something similar with an or2 component to link an external e-stop and a torch crash sensor on my plasma build. eg. If the torch falls off its magnetic mount due to a crash, an e-stop will be triggered. LCNC sees this as an e-stop but of course the active signal can drill into the cause.

rodw wrote:

Somewhere I saw an example of a HAL logic command that fed 4 inputs into the e-stop circuit. All all of the inputs had to be OK or an estop would trigger. I've done something similar with an or2 component to link an external e-stop and a torch crash sensor on my plasma build. eg. If the torch falls off its magnetic mount due to a crash, an e-stop will be triggered. LCNC sees this as an e-stop but of course the active signal can drill into the cause.

I think I would rather have external hardware logic than software logic for the e-stop.

So I came up with this.........

See attached wiring of the e-stop.

tommylight wrote:

That looks O.K.
Does your e-stop cut power to servos, or just enable/disable them?
In case it disables the drives, your config is all good. In case it cuts the power, i would refrain from connecting anything to the e-stop loop, except the extreeme limit switches.
On bigger machines i use 2 limit switches on both sides of an axis, the inner ones wired to software limits and the outer ones wired to the e-stop loop that cuts the power to drives and almost anything else. That limits the usable work area, but it is very useful in case anything goes wrong.

The drives have two inputs, one for the limits and one for e-stop. I do not know what they do different in the two scenario's yet.
Will check that out later in the retrofit.