Gecko G251 and a PLC help

[mattyv83]

Hello Forum,

I am new to this forum and not a CNC person, but I am trying to wire a G251 to a PLC with stepper capabilities and for some reason it isn't working properly(at all). This is the first stepper project I have done so bear with my inexperience.

I have 2 drives in my project and one is from automation direct and I can make it function without a problem. It has built in optoisolation. I went through a fairchild H11L2 optoisolater to the gecko drive. The motor has holding torque, but wont move in either direction. When I hook up to the same plc outputs through the AD driver, it works fine. I am using a 5.1v wall wart for my opto power and I have a 24v and 2.2k resistor going to the input side of my opto. What kind of voltage readings should I be getting across the outputs? I get 3.4v across both step and direction when idle and when the plc sends a command it jumps to 3.8v. Would any of this have to do with my grounds? On the AD drive I am using the same power supply for the PLC and the motor power. On the gecko drive I have a 48v power supply for the motor and the same 24v power supply.

Can anyone offer any advice, suggestions, anything?

Thanks in advance

matt@skabrewing dot com

[Al_The_Man]

It sounds to me initially that you are jumping through too many hoops to get isolation, Do you have any kind of drawing or sketch of your hookup, also what is the nature of the PLC outputs? and what are they powered by?
Al.

[mattyv83]

Wow, that was quick

Here is a link to the manual for my PLC that gives a schematic of how I should hook up a driver that isn't optoisolated:

Its on Page 10-4 figure 10-5. I couldn't cut and paste it into here so forgive me for making you look through the manual

The PLC outputs are 24v NPN. and they are capable of PWM outputs for stepper motor control. I initially tried to go straight from the plc (with a 2.2k resistor) with out the isolaters and essentially the same thing happened. No direction, but holding torque..

Thanks

http://www.tri-plc.com/documents/F2424-UserManual.pdf

[Al_The_Man]

Do you get 0v to 24v transition on the PLC output to start with, you could also put a LED in series with the 2.2k resistor and see the pulses.
Still not clear on your supply commons, the opto output common should be connected to the G251 input common.
Al.

[mattyv83]

Ah ha!! Got it....Thanks. I could be wrong here, but I connected the 5v power supply ground and the 48 v ground and got action...Is this correct?

I've read that the motors get hot, If this thing is operating 12-15 hours a day about two 360 deg. rotations every 3 seconds, will temp present problems? I don't notice the heat build up with the Automation direct driver..Of course it was twice as much as the Gecko.

I am actually going to be running 6 of these Nema 17 motors to align beer cans for facing on our canning line..They will be all condensed into a, well, a space about the size of a six pack. Will heat build up be an issue?

As I mess with this, a little bit as I am typing, I can't seem to get the speed I want out of the drive. My controller is capable of 10k pps. What is the resolution of the Gecko?

Thanks a ton for the help....

Ska Brewing Company

Matt

[Al_The_Man]

It looks like the 5v power common should be connected to the sig Gnd, the 48v common is normally separate.
I don't use Gecko or steppers as a rule, so it may be an idea to shoot a email to Gecko support.
Al.