Issues with stepper motors losing power

[ZASto]

Many drives (read TBxxxx and similar), when Enable is asserted, switch off their output stage and motors are unlocked, i.e. you can spin them by hand - no holding torque.
It is quite common that motors act "weird" while PC is booting, unless charge pump is enabled in Mach3.
Many years ago I made an interface between Mach3 and RZNC breakout board and added charge pump circuitry to be sure that machine will not play silly while booting.

[JAZZCNC]

Where does he say that?.
The op has no mention of getting any movement at all. Only controller fan. All he gets is power to them and motor locking, then power going off when booted.

Slip of the keyboard, it should have read " he says they drop holding torque and WON'T spin when the controller starts up" I wasn't quoting him either.!

That is not the way my CNC works. When the driver is enabled there is a holding torque. When it is disabled the holding torque is lost and I can rotate the motors with my hand. This is the way I want it to work.

Depends on the drives, some do, some don't, some can be configured via software to work either way.
The most common config is the opposite of yours where the motors instantly powered up when power is applied to the drives and drop the holding torque when the enable pin is set. Again this can be inverted on the drive or thru software depending on the drive. This is why the enable pin can be left unwired on most drives.

[A_Camera]

Depends on the drives, some do, some don't, some can be configured via software to work either way.
The most common config is the opposite of yours where the motors instantly powered up when power is applied to the drives and drop the holding torque when the enable pin is set. Again this can be inverted on the drive or thru software depending on the drive. This is why the enable pin can be left unwired on most drives.

I am not sure what you mean by "The most common config is the opposite of yours"... My system works just like are describing. Perhaps you misunderstood what I wrote. Disable = no holding torque Enable = Holding torque the way I see it. The signal can be active low or active high, depending on some other things, but that's a different thing.

You were saying earlier: "The enable won't drop the holding torque, it will only disable the drive outputs so they don't spin, they will still be locked"

The Enable signal controls the holding torque. If the Enable changes state (goes from low to high or high to low) it will enable or disable the driver which will apply or drop the holding torque. On most drivers, if the Enable is not connected (floating) the holding torque is applied and the driver is enabled. The motor is locked only when there is a holding torque (driver enabled). If the driver is disabled and there is no holding torque, the motor can't spin, not even if you apply step pulses. When the driver is enabled the motor is on holding torque but starts spinning as soon as step pulses are applied.

[dazp1976]

I am not sure what you mean by "The most common config is the opposite of yours"... My system works just like are describing. Perhaps you misunderstood what I wrote. Disable = no holding torque Enable = Holding torque the way I see it. The signal can be active low or active high, depending on some other things, but that's a different thing.

You were saying earlier: "The enable won't drop the holding torque, it will only disable the drive outputs so they don't spin, they will still be locked"

The Enable signal controls the holding torque. If the Enable changes state (goes from low to high or high to low) it will enable or disable the driver which will apply or drop the holding torque. On most drivers, if the Enable is not connected (floating) the holding torque is applied and the driver is enabled. The motor is locked only when there is a holding torque (driver enabled). If the driver is disabled and there is no holding torque, the motor can't spin, not even if you apply step pulses. When the driver is enabled the motor is on holding torque but starts spinning as soon as step pulses are applied.

This is why I suggested to check he didn't have settings or the wiring backwards - high/low (if actually wired in that is).
Enabling during pc booting, disabling when it comes to life.

[Steven W]

Hi Guys

Sorry I haven't replied sooner but I've been away for a few days and have also been working on a solution. Thanks for all the responses and debates that ensued!

I am now glad to report that everything is working well. It's a bit of a saga but there were a few things wrong. The other two Dell pcs I was using already had a printer ports installed (by Dell). I don't know if by putting the Moschip pci board in was causing a conflict? I also noticed that even with the cnc controller unplugged from the pc, Mach 3 was not working properly. Somehow it is corrupt. It was a version I got with the Chinese machine. Can't remember if it came as a download or a disc but I didn't have either to hand.

I decided to buy a new motherboard for the old original pc that I knew worked prior to buggering it up last winter. Once I had it configured and reinstalled the PCI board and downloaded the demo version of Mach 3 everything started working perfectly. Don't know why but the address for the Moschip PCI board had changed with the new motherboard but once I figured this out - bingo!

The only issue I have now is Mach 3 in demo mode only which only gives me 500 lines of movement. I could spring a few quid for a proper UK version of Mach 3 but I've been reading up on LinuxCNC and wondered how this stacks up against Mach 3 and how similar is it? Will download a copy and give it a whirl

cheers again for everyone's input

Steve

[dazp1976]

Steve

Did you keep all the old Mach files / hdd from the pc or did you wipe it?.
There'll be a file in the old mach folder called Lic.
This is the license file. You just copy it to the new mach folder.

[JAZZCNC]

I am not sure what you mean by "The most common config is the opposite of yours"... My system works just like are describing. Perhaps you misunderstood what I wrote. Disable = no holding torque Enable = Holding torque the way I see it. The signal can be active low or active high, depending on some other things, but that's a different thing.

Excuse the pun, I think we are getting our wires crossed here.! What I meant was that the standard setup is that the drives have holding torque if the enable is NOT used and if the enable is used then holding torque is dropped when the state changes. The way you described it your drives are set so they need the enable signal to engage the torque, this is opposite to standard setup is what I meant.

You were saying earlier: "The enable won't drop the holding torque, it will only disable the drive outputs so they don't spin, they will still be locked"

The Enable signal controls the holding torque. If the Enable changes state (goes from low to high or high to low) it will enable or disable the driver which will apply or drop the holding torque. On most drivers, if the Enable is not connected (floating) the holding torque is applied and the driver is enabled. The motor is locked only when there is a holding torque (driver enabled). If the driver is disabled and there is no holding torque, the motor can't spin, not even if you apply step pulses. When the driver is enabled the motor is on holding torque but starts spinning as soon as step pulses are applied.

Yes that is the common way it works but it's not exclusive and some drives have the ability to maintain the holding torque when the enable changes it states, they just stop movement, this helps in applications like Z-axis, etc where don't want it to drop when an E-stop occurs, etc. Many servos and some closed-loop stepper drives offer this option with a parameter change.