Run vacuum pump actuator during entire job instead of during each pick

[Steve Richardson]

I currently have pneumatic valves and pump set up with individual actuators and they're working fine.  The valves and pump are currently part of the hierarchy of the head in the config. 

I would however prefer to keep the pump running during the entire job and have only the valves actuated during picks/places.  I'm leaning towards adding an accumulator tank and a separate control loop to keep the system vacuum pressure between set points, much like a commercial air compressor does.  I think this will let me greatly reduce required dwell times.

The documentation mentions OpenPnP should be flexible enough to allow this sort of config, but I haven't been able to figure out how to do it.  Any tips?  I know I can set up a system-wide actuator but not sure how to make it turn on/off with the job and during individual picks that may be done outside of a job.

I simulated the behavior I want by taking the pump actuator out of the head config, and manually turned it on at the beginning of the job, but that is cumbersome.  It would also be nice to be able to pause the job (or next pick) until system vacuum is at an appropriate level, according to a digital input connector to the pressure controller.

thanks,

Steve

[Clemens Koller]

Hi, Steve!

Can't you just ignore the pump switch output?

On a Liteplacer, there is the vacuum pump on an MOSFET output as well as the vacuum valve for the nozzle.
I've replaced the noisy pump of the Liteplacer with a silent aquarium pump, operated from line voltage - always on.
The next pump will be a silent fridge compressor and an air reservoir which will be switched on demand to keep a certain level of vacuum completely independent of OpenPnP / Liteplacer.

Regards,

Clemens

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[Bernd Walter]

On Tue, Mar 02, 2021 at 09:22:38PM +0100, Clemens Koller wrote:
> Hi, Steve!
>
> Can't you just ignore the pump switch output?

On my machine I intended (not setup yet) to do that with special
command features on my gcode board.
Enable pump with startup waiting time, so that the pressure can
build up first.
Don't wait if the pump was already running.
Disable pump delayed - pump continues to run for a given time.
If the pump is needed in time it continues to run and I don't have
the startup waiting time.
If the pump is not needed again in time it automatically turns off.

--
B.Walter <be...@bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.

[scott.t...@gmail.com]

Create an actuator that only sends gcode to turn on the pump. Make that your pump actuator, it'll start when required and not shut off.

Create another actuator that shuts off the pump, call that from a job.finished script.

I was doing this until I switched back to individual small pumps per head.

-Scott

[ma...@makr.zone]

Hi Steve

Just in case you didn't know: you can now actuate Actuators on Machine states:

This is however not related to Job start -> stop but rather to homing -> disable (adding the former is planned)

On my machine I use a hysteresis/"bang-bang" control on a pump reservoir. There are two commands you can define (for Smoothieware) and one waits for the low water mark to be established:

temperature_control.pump.set_m_code 140 #
temperature_control.pump.set_and_wait_m_code 190 #

See also:
https://makr.zone/vacuum-sensor/192/

_Mark

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