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Author Topic: General Config “Charge Pump ON in Estop”  (Read 2582 times)

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Offline kolias

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General Config “Charge Pump ON in Estop”
« on: July 25, 2016, 12:14:09 PM »
What really happens when I check the “Charge Pump ON in Estop” in the General Config?

Pressing my Estop disables all outputs regardless if my BOB includes a SCHP circuitry?
Nicolas
Re: General Config “Charge Pump ON in Estop”
« Reply #1 on: July 25, 2016, 03:15:28 PM »
It kind of depends on how your e-stop button is wired.  My system originally came with the e-stop button only set to turn off the 24vDC to the controller and stepper drivers.  (It didn't even have a mechanism to stop the spindle!)  So I re-wired my system to use the other contact on the e-stop button to connect to the e-stop signal on the board.  This tells Mach3 that the e-stop was pressed (something it didn't "see" before) and stop processing immediately - even before the power can fade out from being cut off.

So first question is, does Mach3 go into Emergency Mode when you activate the e-stop button?  (i.e. Is the switch actually wired to your BOB/Motion Controller card?)  Many of the less expensive systems have the e-stop button wired the way mine was.  Others put it in the same switch/wiring system as the limit switches like in the wiring diagram at the back of the Mach3 manual.  I like to have it on its' own separate signal, especially since my BOB has an input pin labeled for such use which was originally not wired.  Fortunately, my e-stop button had two contacts; one normally closed (open when e-stop pressed) used to cut the 24vDC power (I may remove this one later so that the system is still in an operational state) and one normally open (closed when e-stop is pressed) to send an "active low" signal from the "Common" pin of the board to the e-stop signal pin.  Of course I had to configure this pin in the Inputs tab of the Ports and Pins configuration.

Once you have your e-stop actually communicating with Mach3 (which it may already be) then it's beyond my scope of knowledge in terms of the Charge Pump usage as my system is not currently using that.

Hope this helps,

Stephen "Highspeed" Kruse
Re: General Config “Charge Pump ON in Estop”
« Reply #2 on: July 25, 2016, 03:34:10 PM »
It means just what it says.
Mach3 outputs a 5kz signal when the program has control. Activating the motors before Mach3 is fully loaded can result in the machine moving under power, which can be dangerous. Once Mach3 outputs the signal, a circuit board (the charge pump) operates a relay. The relay is usually wired to the Enable input on the drivers. Until the Enable circuit is activated, the motors cannot move.

In the Output menu, the Charge pump has a specific position, and setting for Active Hi, or Lo, and output pin number.

The Estop will disable driver output, but keeping the (Charge pump on in Estop), will keep power on the driver, just no motion, thus holding the current step position.
If the motors are moving rapidly, and you hit Estop, you will likely lose position anyhow, as it may take a few steps for everything to come to a halt. This is why it is best to hit Feedhold first, then Stop.

If the charge pump relay is off (no power to the enable circuit), when the Estop is removed, on restart the motors can take small jump to the closest magnetic pole, which may or not be the right direction.

Mach3 will work either way you set the function.

Offline kolias

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Re: General Config “Charge Pump ON in Estop”
« Reply #3 on: July 25, 2016, 04:24:21 PM »
My Estop is wired to a pin on the BOB and +5V and when I hit the Estop everything stops except the spindle which I have wire it thru an ON/OFF switch in my control panel (I want it like this).

I know I can have the Estop wired as hardware disable and for now it is wired as I said just like an Estop only.

I try to understand the meaning of the “Charge Pump ON in Estop” in the general config.

If my BOB does not have a charge pump and I wire the Estop as hardware disable would this stop the power to the drivers (besides stopping the motion)?

If the above is true, then what is the meaning of “Charge Pump ON in Estop?”

Nicolas
Re: General Config “Charge Pump ON in Estop”
« Reply #4 on: July 26, 2016, 12:17:37 AM »
The "Charge Pump" is an actual device that can recognize the 5khz signal output by Mach3. It is wired into the outputs per the Ports and Pins using one of the output pins. It runs on 5 volts, and when it sees the signal, it operates a relay. CNC4PC sells such a device, and also some of the BB have this capability built in.
The CNC4PC Charge Pump also has a red LED that turns on when the signal is received, making setting it up much easier.

As I said in a previous post, you can select whether the "Charge Pump" stays on during an Estop. The Charge Pump relay is commonly used to control the EN "enable" signal on the drivers, thus keeping the machine in a no-motion state until the Mach3 program is loaded, and has control over the Drivers.

It is not necessary to wire the drivers power into the Estop switch, as the Estop state is seen by Mach3 as a "no steps output allowed" condition, and the motors cannot move.

The Estop is an "Input" signal to the Mach3 program, and the "Charge Pump" signal is an output signal by the Mach3 program. They are two entirely different things in the operation of the Mach3 program operation.

Thus, the "Charge Pump ON in Estop" allows the drivers to have power, holding torque and position during the Estop condition, since the Charge Pump is in control of the 5v. Enable signal to the Drivers. This assures the machine current position will not become altered due to a power-down state of the drivers.

Most stepping motors are 200 full pulses per revolution, but micro stepping settings break this single magnetic pulse into more "partial positions" in the magnetic field.  If your machine is put into Estop, and the motor happens to be in a "partial step position" due to micro stepping, a full Driver Power Off state will lose this partial state position. When power comes back ON, to the Driver, the motor will assume the closest full step position, and not be in the same position as before the Estop.

The Charge Pump is also known as a "Safety Charge Pump", due to it's function in the machine Start-Up.  If you do not have a Charge Pump wired into your machine, it will still function properly as long as the Driver power is not disabled during an Estop. Since you don't have an actual Charge Pump on your machine, the General Config setting does not apply to your machine.








Offline kolias

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Re: General Config “Charge Pump ON in Estop”
« Reply #5 on: July 26, 2016, 03:50:51 AM »
Thanks for your time mrprecise44, I know understand.
Nicolas
Re: General Config “Charge Pump ON in Estop”
« Reply #6 on: July 26, 2016, 11:12:53 AM »
You are more than welcome. Many things in Mach3 are not "intuitive", and it take time to fully understand.