Synchronize between 2 different Motors.

[Willy]

Hello,

I am to new PLC and my friend will do most of the programming for the DL205 with a 260 CPU. My questions are:

1) Is possible to program H2-CTRIO to synchronize 2 different servo-drive motors.

My application requires 2 different ratio of motors. The top motor send a stroke in one full revolution where as the bottom motor is 1/2 turn of the motor. So the top stroke should hit the bottom part at 0 and 180 degrees.

2) Do I need to have another 2 additional absolute encoder for this function.

3) Will there be problem with accel and deccel because of the different size of motors. I know there is no problem with my CNC machine that I use 2 servo drives in one axis but is the same size.

thanks

Willy

[Greg]

Answers:
1) No. The CTRIO has no internal synchronization function. But I'm not clear whether you mean you are wanting to control 2 motors (which have different resolution) or whether you are merely reading the encoders on these two motors that have different resolutions. If you are controlling them, you would have to do the math and start both motors at the same time and run to a limit, or a calculated position. If you are merely reading the encoders then the CTRIO can scale the encoder inputs to a rate or position of your choice.

2) The CTRIO inputs do not support absolute encoders. It supports single-ended encoders, or quadrature encoders.

3) The accel & decel functions are functions of your motors, and you can set these parameters to whatever values you want in the CTRIO configuration.

[Willy]

Hello Greg,

May be I try to explain a little more is controling a sewing machine, the top motor is turning the needle at one full revolution(turn) and bottom bobbin is half revolution(turn).

So for every needle stroke the bobbin is only turn 1/2 revolution. The needle and bobbin must be in sync at fit position otherwise the needle will be break. Let say the needle must hit the bobbin at exactly at 0 and 180 degree -+2 should be okay.

Do you think Direct Logic PLC will work for this case?

Thanks

Willy

[Greg]

That would be very difficult to assess. The DL-PLCs along with a CTRIO could handle it as long as the speed of the machine was not too great. Synchronization using electronics is always a "iffy." It would seem to me if the speed of the machine is fast and synchronization of the two motions critical so that needles are not broken (among other things) that there should be a mechanical coupling of some sort instead of depending upon electronic sync.

Application design is based on much research, study, creativity, skill, planning and a good percentage of trial and error. So, you could buy the PLC equipment from Automation Direct and attempt to get them to work in a "mock-up" or something. They have a 30-day return policy. If you can't get it to work within that time, you can send the equipment back for refund.

[Controls Guy]

Why not just do this with a 2:1 mechanical reduction, gearbelts or something?  Then they CAN'T get out of time.  Seems like a lot simpler solution to me.  Even if for some reason you have to control them separately, a mechanism that indexes the bobbin very close to a half turn and in done such a way that it doesn't accumulate positioning error, controlled by a photo or fast prox that senses the needle mechanism seems like an easier go.

Using electronic automation is fine, but only when it offers some benefit.  If mechanics are easier, will perform more reliably, or have cheaper replacement components, there's nothing wrong with considering them as an alternative.

[Controls Guy]

They have a 30-day return policy. If you can't get it to work within that time, you can send the equipment back for refund.

Incidentally, about that.  What you're saying is the same thing I've always been told and by VAR's like Quantum as well, but recently I've got several boxes sealed with a label that says if I break the seal, I'll have to pay restocking if I return it, which is in contradiction of the other statements.  What's the real story?

[BobO]

Incidentally, about that.  What you're saying is the same thing I've always been told and by VAR's like Quantum as well, but recently I've got several boxes sealed with a label that says if I break the seal, I'll have to pay restocking if I return it, which is in contradiction of the other statements.  What's the real story?

Sorry, couldn't tell you...that's ADC's policy, and I actually don't know.

We just deal with the crap that ADC returns to us after you guys run it on a machine, in a sawmill or similarly unsavory environment, then unsuccessfully attempt to peddle on EBay, and then return to ADC as a last resort...claiming it was 'broken'.

[Controls Guy]

We just deal with the crap that ADC returns to us after you guys run it on a machine, in a sawmill or similarly unsavory environment, then unsuccessfully attempt to peddle on EBay, and then return to ADC as a last resort...claiming it was 'broken'.

What, you mean we're not supposed to do that?   

[BobO]

What, you mean we're not supposed to do that?   

No, you're supposed to return it to Walmart for store credit.