forum.cncdrive.com

I have a relay->contactor that turns on my stepper motor power supply (a chonky, noisy and power hungry Cisco Catalyst 4500 2800W / Sony APS-172). My first thought was to have the power on whenever UCCNC was out of reset and / or the steppers were enabled.

While it technically works I have some questions.

First, when UCCNC is first started it seems to cycle the outputs that are triggered by the LED status, relays and contactor go on and off really fast. Tried linking the output trigger to LED 25 (reset) as well as LED 139 (EnableXAxis) and both give the same result. Is there a way to get around this so I don't end up damaging the power supply? Force these variables to be always off before startup or something? Some sort of macro that follows the reset button but requires an actual button click?

Second, if I understand UCCNC correctly, triggering a limit sensor, editing some settings and applying them etc will trigger a reset and disable the motor axis? Is there a way of changing this, so that for instance, the machine just stops without resetting, or disables the steppers but doesn't reset? I realize the answer is probably soft limits but nevertheless ...

Any other thoughts on how to cleverly integrate the contactor operation in a way that is automatic and doesn't cause unnecessary wear and tear?

Use a charge pump relay to enable all other outputs (the power line for all other relays). By default the charge pump is on when the reset is cleared, but you can set it to be always on. Always on means that UCCNC is up and running, the outputs are set to their default value. Here you can find information about charge pump circuits. I usually build the 74HC14 circuit, but there are more simple circuits on the web.

Second, if I understand UCCNC correctly, triggering a limit sensor, editing some settings and applying them etc will trigger a reset and disable the motor axis? Is there a way of changing this, so that for instance, the machine just stops without resetting, or disables the steppers but doesn't reset?

Setup your limits switches as Input triggers, and assign Cycle Stop to them. Do not enter any port and pin numbers for Limits on the Axes setup pages.

Good input, thanks! While I read up on charge pumps, I added the output pin for the relay to the startup and shutdown macro files as a temporary solution.