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Author Topic: Shorting output pin for disabling gecko G251X  (Read 3137 times)

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Shorting output pin for disabling gecko G251X
« on: August 06, 2013, 08:00:22 AM »
I'm currently wiring up my mill to a CSMIO/IP-S using geckodrive G251X's.
As opposed to the geckodrive G203V where the disable pin needs 5V to disable - the G251X disable pin needs to be connect to ground of the power supply.
I could do it with a relay, but I'd rather keep the setup simple.
Would changing polarity for a set of output pins do the trick?

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gallenat0r

Offline mmoe

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Re: Shorting output pin for disabling gecko G251X
« Reply #1 on: August 07, 2013, 02:11:10 AM »
It's best to use relay in my opinion. The main issue is that I'm guessing the power supplied to the disable pin is provided internally by the Gecko drive itself, so I'm not seeing how you could complete the circuit through the outputs, which are powered by their own power supply. You put 24V and ground to specific pins to power a small group of outputs (each group requiring their own power supply/ground). They don't function without the power supply and will only complete a circuit with that power supply. For the $15 that a relay costs, I think it would be risky and foolish not to just buy one and do it right. I don't think you could expect CS Labs to warranty the controller if you connect it that way unless you specifically ask them if it can be done.

My experience with the outputs from the CSMIO IP-A is that relay with diode will not function properly. I had tried several out with no success and then replaced them with more simplified relay that just had a straight LED indicator, and it worked just fine. The part number for the relays I found work well is Idec #RU2S-D24 (2 pole relay) and Idec #RU4S-D24 (4 pole relay). I also had no trouble with a basic non-LED relay with 24v DC coil, so it seems like the Diode based ones are the ones to stay away from. They cause a current draw that exceeds the 250ma limit (double check the number for yours, I'm going off of memory), which gives a fault in the CS Labs plugin for whatever output you have connected to it.
Re: Shorting output pin for disabling gecko G251X
« Reply #2 on: August 09, 2013, 10:58:32 AM »
I found some small relays at element14 with DIN sockets and they are now installed.
It works like a charm :)

Now is there a way for the CSMIO to have outputs default to high so the drives are disabled when mach3 is not running?

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gallenat0r

Offline mmoe

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Re: Shorting output pin for disabling gecko G251X
« Reply #3 on: August 09, 2013, 01:42:04 PM »
I'm not quite sure what you are asking for. It sounds like you want the controller to have an active output when Mach 3 is not running? If so, then no that is not possible. The controller will basically go to a state of "reset" when it looses connection to Mach 3, regardless of whether or not the cause of the disruption is intentional or not. If an output could stay active when the connection between Mach 3 and the controller is lost, that could result in a very dangerous condition, so by design the controller will stop everything if the connection is lost. I've tested this and found that it takes about 1-2 seconds during operation for the controller to shut down the outputs and any motion it may be running when the connection is lost, so it isn't quite immediate, but it is fast enough that it would prevent dangerous conditions.

Normally, you would use an active output signal to turn the servos on, so it sounds like you are doing it backwards by using an active output signal to turn them off. A standard relay like those I suggested have the ability to either open a circuit when the coil is active (on signal from controller), or close a circuit when the coil is active depending on how you wire the relay. If the relay is a 2-pole relay, there should be a total of eight connection terminals. Two of them are the coil circuit, which is hooked up to the output signal from the controller. The other six form two separate switches through the relay, so basically three terminals per switch. Those three terminals produce one normally open switch and one normally closed switch. If your drives turn on by shorting the enable/disable pin, then you would set it up so that the circuit is connected to the "normally open" side of the relay. If your drive is turned off by shorting the enable/disable pin (it sounds like this is the case), then you would set it up so the circuit runs through the normally closed side of the relay. In the case of the latter, when you start Mach 3 it will be in reset and the drives will remain off until you press reset. Once you press reset, the output you have designated for this purpose will become active and the relay will open the circuit, allowing the drives to turn on. When Mach 3 goes into reset, the output will deactivate and the circuit will close again, causing the drives to turn off and stop any motion that may currently be happening. If Mach 3 is shut down, the output will also remain inactive, and the circuit will also remain closed leaving the drives off.  
« Last Edit: August 09, 2013, 01:45:34 PM by mmoe »