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nic6911
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« on: February 29, 2012, 10:24:42 AM »

Hi. I am the happy owner of a gecko G540.
I have a problem though, or two that is.

I use one of the outputs to set my VFD drive in run mode and start the spindle. The problem is that if the gecko is off the output goes on... but if i turn on the gecko the output goes to off unless i enable it in mach3. The resistance between 0V and the output is to low to not enable the output when the gecko is without power. I can off course always turn the gecko on with the VFD and there is no problem. But when i turn of the system, the VFD will start to spin for a second until the capacitors in it has discharged...
What to do!?

Then i have another little problem. If i press the big reset button in mach the gecko does not disable!? So if i press my emergency stop and release again, the gecko just enables without me having to reset it in mach3.. For security reasons i really wan't the mach3 to do disable the gecko when i hit the reset and enable when i hit it again.

Help will be appreciated!

Regards Nic
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Fastest1
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« Reply #1 on: February 29, 2012, 11:34:55 AM »

Connect and use the SCHP (charge pump in the outputs section of Mach) feature. This will disable any output until Mach is operational. It tells the G540 to not do anything until it get this signal. Do you have your Estop enabled and hooked to the correct pin? You dont have a jumper across the E stop input for the original testing do you?
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Fastest1
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« Reply #2 on: February 29, 2012, 11:37:47 AM »

The E Stop should stop all motion and signal possibilities. It will not disable the G540, the steppers should be locked upon E Stop. If I am understanding you correctly, are you expecting the steppers to be able to move by hand when the Gecko is disabled (via the E Stop)?
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nic6911
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« Reply #3 on: February 29, 2012, 03:36:36 PM »

If i e-stop my g540 the diode will be red and i can move the steppers by hand. But if i release the e-stop the diode goes green again without me having to press the resetbutton in mach3. On other driver boards i had to press the reset button in mach3 to enable the board again...
This is a good feature since you can then use the reset button in mach3 to disable the driver board and eventually move the steppers by hand if they reach a limit switch for example.. As it is now i have to turn the power of to get the stepper away from my limit switch and then turn on the power again! or i have to press my e-stop button.

Regards Nic - and thank's for the reply's so far Smiley
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Fastest1
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« Reply #4 on: February 29, 2012, 03:55:15 PM »

There are 2 different things at play. If you hit the E Stop, all motion should cease. My understanding is that the Reset on Mach should do the same thing. However there is an ability on the G540 to disable the drives (IIRC) but this would involve using a separate switch to disable. I might have always misunderstood the Reset however it stops all motion including the spindle on mine. I dont know if it is doing it thru the contactor or via software though? (my physical E stop kills the contactor)
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nic6911
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« Reply #5 on: March 01, 2012, 12:10:08 AM »

Yes if i hit the e-stop the motion stops and the gecko led goes red. I can now move the steppers manually. If i press reset it also stops, but the led is green and i can not move the steppers manually.
The spindle will stop in booth ways since my e-stop goes through the g540 and my spindle vfd is started by the output from g540.
I don't get it.. other cheap driverboards wil disable when hitting the reset button in mach...

Do you use the output to enable the contactor? and do you have the same problem as me? as i wrote in the first post the output enables when i turn off the power to the gecko, but only the output where the relay is connected. If i measure on the other output there is no contact to 0V. It is like the internal resistance for the outputs are to low...?
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Jeff_Birt
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« Reply #6 on: March 01, 2012, 09:06:24 AM »

For the VFD issue - use the Mach output to drive a small relay, use the relay to send the enable signal to your VFD. This will isolate the G540 from the VFD. The G540 will also not turn on the relay unless you tell it too. For VFD's I usually use output 1 of the G540 to power a relay/contactor to apply power to the VFD and output 2 to drive a small relay to start/run the VFD. This way the VFD/spindle will only have power when Mach is out of Reset mode and you still have an isoalted start/run for the VFD.

ESTOP - Neither the EStop input on the G540 or the any output from Mach3 make up a 'real' EStop. In industrial machines when you hit EStop all drive power is removed from the things that move. This is done by removing the input power from the drive power supply (typically) by use of a contactor. For small machines you may find that the 'breaking' current rating of an EStop switch is adequate to interrupt power to the power supply, for larger machines you will need to use a contactor. NOTE: technically speaking a 'safety' type contactor should be used, sometimes called an MCR. These as basically really fancy contactors that have been designed and tested so they work with a very high degree of certainty. If your running a Taig mill this may be over kill, if your running a large router it might make more sense.
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Happy machining , Jeff Birt
 
Fastest1
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« Reply #7 on: March 01, 2012, 02:32:07 PM »

Jeff, though a great description of what "should" be done and what is acceptable on our hobby machines. One of his questions was, "does pressing the Reset button on the Mach page allow the steppers to freewheel (not locked electrically) on the G540? I have mine reallocated and in a test with a Smoothstepper and nothing is configured correctly or safe during this.
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Jeff_Birt
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« Reply #8 on: March 01, 2012, 03:10:48 PM »

Quote
One of his questions was, "does pressing the Reset button on the Mach page allow the steppers to freewheel (not locked electrically) on the G540?

The G540 will not disable the stepper motors when the Reset button in Mach is pressed. This is related to my point above that the Reset button in Mach does is not an EStop, so it should not be thought of (or used) as such.
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Happy machining , Jeff Birt
 
nic6911
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« Reply #9 on: March 01, 2012, 03:38:45 PM »

I know that the estop in the g540 is not a real estop. I would use a relay to switch of the 230V to my dc supply. It is not a good idea to switch off dc power with high current, unless you use a diode to protect things. And as Jeff says in some cases it would have to be a certified safety relay or other safety measures as mentioned in DS/EN ISO 13849-1. But this is just a hobby machine, so I don't bother.

The right way then is to press the estop and turn my steppers by hand if i get stuck at the limit switch Smiley

The relays I thing for the VFD I could try, but the inputs on my VFD is sink, and the 0v on the VFD and gecko have the same potential. I have not measured the current draw but i recond it is less than that of a small DC relay.
But okay it is worth a try Smiley

I don't want to switch a contacter for the VFD supply. I like it small and simple. I will live with the drawbacks then Smiley
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