G540 - 4 motor connection problem

[Neale]

As Clive says, the kits are often put together using less than ideal choices of components. In this case, I would guess that the kit uses a switch-mode power supply because these are smaller, lighter, and in particular cheaper than a linear supply, which is the preferred option from a purely technical viewpoint. The linear supply can cope with peak overload without breaking into a sweat where the SMPS can trip internal overload protection. I'm a bit surprised as well that there is a problem, though, but seeing that it appears to be load-related, and is a bit variable suggesting that perhaps it is when all motors are trying to deliver pulses simultaneously which won't happen all the time, maybe it is the PSU. Does seem on the face of it to be the most likely issue. My own machine uses small, cheap SMPS boxes for control circuitry where the load is smaller and well-defined (very cost-effective here) but I use a linear supply for the stepper drivers.

[Clive S]

If I am not mistaken depending on the how the drives are set the motors will draw more current when stationary

[m_c]

I would expect the internal filtering capacitors of the Gecko drives to minimise any harmonics that could cause high instantaneous current use.

However, what I'm wondering is what is the actual fault being caused?

[komatias]

With the 3.5A tuning and your power supply the gecko should work 100% fine. I suspect there is something tripping the chargepump.

What are you using to drive the Gecko? parallel port? Is that conking out and causing the chargepump to go low?

[dachopper]

This is my power supply http://www.automationtechnologiesinc...upply/48v12-5a

I have the G540, connected with the DSUB ribbon to UC400ETH controller, then that goes Cat5 cable to a switch, and cat5 to my laptop.

When the fault occurs, the connection between the UC400ETH and Laptop and UCCNC program looks normal ( the G540 disables the servo's from moving, and the UCCNC software shows that the motors are still being told to move without any limit switch activation.
)

I noticed aswell, a little noise from the servo's when they are stationary and they are all connected, but less when there are 1 or 2 or 3 motors connected is this normal?

I've checked the resistors and they are 100% correctly installed, and re-wired the power supply to G5540 + and - with other 14G braded wire last night

[dachopper]

Another thought

To troubleshoot the power supply, I have a Mastech 30 Volt 10 Amp variable DC switching power supply.

Should I plug this in ( although it's only 30 volts, and the other one is 48 volts ) and see if there is a difference?

Nick

[dachopper]

I experimented again with the power supply and g540 , thismorning.

My other power supply, is only 30 Volt max 10 amps, but I can see the current draw on the system was down around 2-3 amps ( don't know how accurate that is ) I could not get the fault with the other system.

I then tried the keeling 48 volt 12.5 amp
with voltmeter on the output, it was steady but faulted at 48 volts, I adjusted the voltage pot to 49.9 volts, again stable, the multimeter coult not detect movement, but the fault happened faster at 50 volts, I dropped voltage to 46 volts, and faulted after 5 minute, then I tried 44 volts, and it took lots of simultaneous input, but it eventually gave a fault at 44 volts, I wound the pot all the way back, so it's now at 42.5 volts, and there was no fault so far.

sound like there is a feedback issue coming from somewhere?

Is there anything I can do to try make it work at 48 / 50 volts

[Clive S]

Personally I would build a toroidal transformer type power supply

[m_c]

I experimented again with the power supply and g540 , thismorning.

My other power supply, is only 30 Volt max 10 amps, but I can see the current draw on the system was down around 2-3 amps ( don't know how accurate that is ) I could not get the fault with the other system.

I then tried the keeling 48 volt 12.5 amp
with voltmeter on the output, it was steady but faulted at 48 volts, I adjusted the voltage pot to 49.9 volts, again stable, the multimeter coult not detect movement, but the fault happened faster at 50 volts, I dropped voltage to 46 volts, and faulted after 5 minute, then I tried 44 volts, and it took lots of simultaneous input, but it eventually gave a fault at 44 volts, I wound the pot all the way back, so it's now at 42.5 volts, and there was no fault so far.

sound like there is a feedback issue coming from somewhere?

Is there anything I can do to try make it work at 48 / 50 volts

Provided you're remaining below the maximum voltage of the gecko drives, and allowing a reasonable safety margin, it should make no difference.

I can't remember, but are there any LEDs on the G540 to let you know any statuses?

I'd suggest temporarily disabling the chargepump input on the G540, and see if fault still occurs. It could be a noise issue that with the higher power, the G540 isn't seeing a good charge pump signal, so it is disabling all the drives. However if that was the case, I would expect problems with the step/dir signals aswell, however that probably wouldn't be noticeable if you're not actually working the machine to notice a position loss.