On Wed, 23 Oct 2019 17:16:39 -0700 "John Dammeyer" <[email protected]> wrote:
> I've added back the safety aspect of an ESTOP event shutting down all high > voltages. The low voltage 24V stays on as does the PC/Monitor and the AC to > the PMDX-126 BoB. Ie. I have two 220VAC circuits. One for all the Motor > power and one for the Control power. Only the Motor Power is removed. > > Now click on the little orange icon to re-enable the system, ENABLE goes > active and the AC Motor Power Relay switches ON. > > Interlocks prevent this while: > 1. An ESTOP is still pressed > 2. Spindle Motor Switch is in ON position, > 3. Limit Switches are not in override if they were the cause of the > ESTOP in the first place and are still activated. > > The ENABLE from the PC goes through the BoB and out to the various drives. > This happens faster than the high voltage power supplies for the drives. > > Is there a way to delay the ENABLE out? You put a delay block on ENABLE out enable flank? > Or will I be forced to build a circuit that makes sure the high voltages are > within range and use the output of that to gate the ENABLE? With a DC servo cutting gate driver voltage is not enough in case transistors fail in opposite directions, guess it's not unlikely to happen if servo is overloaded with a resulting over current in transistors. > What's everyone else doing? For the emergency stop I would buy a real emergency button and connect so that power is cut to make machine stop. Then pressed it should also be sensed so that emergency stop in Linuxcnc is toggled. I would not trust emergency button in Linuxcnc, the computer may stop responding for many reasons. An extra switch maybe with personal padlock might also be good then working with the machine, Injection mold machines at least sometimes also have a mechanical lock. Programming errors or other logical errors are common. Safety circuit should be simple to check and understand though there might also be a cases there a complex sequence which must work to keep alive is suitable, I would guess to succesfully reading a bar code or QR code to keep alive could be made so that likelyhood for an error in wrong direction is very low. Put a toggle signal in Linuxcnc, send it out on all motor driver outputs to a transformer connected to a safety relay which is connected in series so that power is cut if signal is not regularly toggled would probably add some safety but in case encoder signal is lost a servo drive is likely to move to one of the end stops. _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
