Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: joeaverage on March 21, 2019, 01:56:48 AM

Title: Do you use a Charge Pump?
Post by: joeaverage on March 21, 2019, 01:56:48 AM: Hi All,
just trying to get a feel for the numbers of people who use a charge pump to 'safe' their machine.

Thanks for taking the time to respond.

Craig
Title: Re: Do you use a Charge Pump?
Post by: Tweakie.CNC on March 21, 2019, 02:34:24 AM: I have never found the need to use the charge pump.
Title: Re: Do you use a Charge Pump?
Post by: joeaverage on March 21, 2019, 02:37:58 AM: Hi Tweakie,
ditto.

Craig
Title: Re: Do you use a Charge Pump?
Post by: reuelt on March 21, 2019, 06:44:56 AM: Why use the CHARGE PUMPS.
Mach3 outputs a constant pulse train of approximately 12.5 kHZ (5kHz for laser) on one or both of the parallel ports whenever it is running correctly. This signal will not be there if the Mach3 has not been loaded, is in EStop mode or if the pulse train generator fails in some way.

If your MACH3 parallel port kernel speed is set at 25,000Hz, it is unlikely that the charge pump will work correctly since the pulse freq could be only about 2K instead of 12.5K.

The purpose of the Charge Pump is mainly SAFETY but may also protect material, tools and even the machine from accidental damage.

A good Break Out board (BOB) with a “Charge Pump Circuit” will stop all motors + Spindle + pumps etc UNLESS the capacitor(s) had been CHARGED PUMPED UP by the pulse train(s) of 12.5KHz from MACH3. That means that nothing will move when Windows Powers Up, or Shutdown or when Mach3 program is frozen - since that (CHARGE PUMPED) capacitor(s) will discharged quickly to 0 volts and all motors get disabled.

People who invested in the Gecko G540 motion controller and use the default XML from Gecko are likely to have the CHRGE PUMP working correctly on MACH3 already.

Cheap BOB that do not have a CHARGE PUMP CIRCUIT often have an “enable pin”. An enable pin will not be as good as the CHARGE PUMP but is better than everything ALWAYS ON. If you use the enable pin, an EStop mode will allow you to manually move the axis by manual cranking/rotating. It will also cool down the motors when EStop button is pressed or limit switch is activated.

If on booting up Windows and MACH3 is not running and you have not press RESET YET but, you find that the spindle is already spinning or pumps already pumping or Stepper motors already activated, you can do something about it...by getting the CHARGE PUMP(s) working.

If External Motion Controllers cannot support charge pump correctly on all the ports they claim to support, there is a danger that MACH4 could turn out to be less SAFE than MACH3 with two Parallel Ports. So feedback to the vendors.
Title: Re: Do you use a Charge Pump?
Post by: olf20 on March 21, 2019, 07:18:50 AM: Have never used it.
Watching.
olf20 / Bob
Title: Re: Do you use a Charge Pump?
Post by: ger21 on March 21, 2019, 11:56:05 AM: I use it in conjunction with a Safety Relay as part of my Estop circuit.
You can't power up the system until the control software is running, and if the software or PC goes out, the system is powered down automatically.
Title: Re: Do you use a Charge Pump?
Post by: TrisWood on May 17, 2019, 01:50:50 PM: Hi...I believe the original intention of Mach was to indicate when the system was either booting up or closing down and motion can be inhibited during this period.
My experience has always been to use any watchdog timer/charge pump signal output in the E-STOP string, this inhibits or shuts off any power devices, motors, drives etc.
This allows for the eventuality of a PC crash or shut down and when powering up/down to disable the rest of the system.
Obviously there is no point in drives obliviously controlling motors when the brain (PC) is dead.
Especially in such systems as Mach where the controll loop is either open (steppers) or not closed back to the servo controller.
Title: Re: Do you use a Charge Pump?
Post by: RICH on May 18, 2019, 05:04:53 AM: Never used a charge pump.
RICH
Title: Re: Do you use a Charge Pump?
Post by: joeaverage on May 18, 2019, 05:26:34 AM: Hi All,
kool...we are starting to get some numbers.

I think we all know what a charge pump is and what its supposed to do but what I wanted to know was how
many can be bothered with it.

I hope more people will vote.....the more who vote the more illuminating is the result.

Craig
Title: Re: Do you use a Charge Pump?
Post by: MN300 on May 18, 2019, 07:24:44 AM: A related question is whether people have an E-Stop circuit that breaks power to motors and lasers rather than just the control wiring?
Title: Re: Do you use a Charge Pump?
Post by: Tweakie.CNC on May 18, 2019, 10:45:08 AM: Quote from: MN300 on May 18, 2019, 07:24:44 AM
A related question is whether people have an E-Stop circuit that breaks power to motors and lasers rather than just the control wiring?

I have both.
The software polled EStop and a contactor controlled AllStop which disconnects power to everything except the PC, associated motion controller and screen. Although it is there and always available for an emergency AllStop has not been used in years.
Title: Re: Do you use a Charge Pump?
Post by: ger21 on May 18, 2019, 11:03:36 AM: If you're using the Charge Pump, it ideally would tie in to the Estop loop, so that either the Charge Pump or an Estop button will kill power to everything.
Title: Re: Do you use a Charge Pump?
Post by: Tweakie.CNC on May 18, 2019, 11:09:35 AM: The difference between EStop and AllStop can perhaps be likened to 'turning off the switch' and 'pulling the plug'.