[la_coterie]

Oh?

what was (is) the problem then? are teh servo's not brushed ones?

[h_2_o]

the Inductance was incorrect to work with the gecko drives plus the differential encoders made it worse off.

[ViperTX]

Well Gecko had a differential to single ended adapter at $15 or so each. What was wrong with the inductance?

[h_2_o]

from talking with mariss for about an hour to an hour and a half today (all good info) he came to the conclusion that it would cost me more to get these servo's going compared to just purchasing new servo's. as for the inductance i have it writting down and i believe he said that the inductance was too low and needed to be higher. I could have that part backwards. he also never mentioned a differential adapter of any type.

[ViperTX]

Well check with Rutex...before you branch off and buy new servos.

[Torchhead]

If the board has optoisolated step and dir outputs the Opto outputs need a common ground with the step and direction side. The Gecko also has opto inputs. There is no advantage to driving an opto with an opto. If you don't get the power and gounds sorted out you won't get a signal. With no signal the Gecko should "hold" the motor (hum comes from the dithering between encoder lines). If you have a runaway where the motor takes off in a direction then either the encoder signals are reversed or you have lost one of the encoder legs. You can use a differential encoder as single ended simply using the A and B only channels. They way you had it to begin with sounds like the Gecko was working but you were not getting proper signals. It could be a host of things including the wrong pins setup in MACH. Also the 320/340 series has the option to run the Gecko input opto from common + or Common -. If you are driving the step and dir inputs through another opto you will need to make sure the outputs of the breakout opto have a ground reference to a floating supply of +5 and you have the Gecko set for +5 common.

This "double opto" thing can get complex in a hurry.

Once you get it stable so the motor is locked, and hums slightly and it will "fight" you if you try to rotate the shaft then the motion problem has to be in the signal side of things. Contact your breakout board vendor for help setting things up.

[h_2_o]

again i spoke with mariss for quite a while on this and his main concern was not the encoders but the servo motors inductance not being compatible with the gecko servo drive.

as for what is going on next, not sure just yet, but i will check out all my options before i do anything.

thanks again for all the help guys

[Torchhead]

With all due respect to Mariss I don't think low motor inductance would cause you to get no response on the step outputs.

You never said how the Common pin on the 320 was set. The parallel port on most computers will not source enough current to turn on the opto's in a Gecko. Some will "Sink" enough current, meaning the outputs are active low but to run in that mode you HAVE to have the +5 Common selected AND have a source of +5 referenced back to the signal ground. In most boards that would be PC ground. Something has to power the Gecko input optos.

A few minutes with a meter on the Dir inputs on the Gecko while changing directions via jog keys in MACH would answer a lot of questions. The step pin changes too fast to get much meaningful info with a meter.

The opto inputs on the Gecko HAVE to have a return current path. In operation where the Gecko is used in Common +5 mode and a source of +5 is used on the Com pin (with it's ground referenced to the proper place) the Step and Dir pin going low (sink) turns on the opto.

Maybe I did not go back far enough in the thread and read all of the posts and you have already established that you are getting the proper signals at the Step and Dir to the Gecko's. If that is the case then I'll just butt out and let the other suggestions roll.

Tom Caudle
www.CandCNC.com

[h_2_o]

[QUOTE=Torchhead;223723]You never said how the Common pin on the 320 was set. The parallel port on most computers will not source enough current to turn on the opto's in a Gecko. Some will "Sink" enough current, meaning the outputs are active low but to run in that mode you HAVE to have the +5 Common selected AND have a source of +5 referenced back to the signal ground. In most boards that would be PC ground. Something has to power the Gecko input optos.[QUOTE]


sorry the common pin was set back to the grd on the external psu for the encoder. I was told by mariss that this was correct. I can not argue one way or the other on why the motors didn't work with the drives, just that this is what i was told.