Created Date: September 21,2017

Created by: automa

We have an application using two Lexium M drive steppers on two rotary tables. We have many of these machines utilizing the Do more with the ctrio card and they all work great. We have decided to move to the brx for the new machine but cannot get the motion to work repeatably. We have been through every instruction, wrote two different programs to no avail. Finally today we decide to just throw a do more with the ctrio card on the system and it worked flawlessly. Any ideas? Anything that I may be missing? we are using the BRX specific motion instructions.

Created Date: September 22,2017

Created by: Tinker

Of course a common reason of non-repeatable motion in stepper systems is the open loop motor missing steps due to various mechanical problems, but the fact that the system works with the CTRIO conveniently eliminates that whole branch of potential issues (well, probably, there could conceivably be resonance issues due differences in ramp generation, but if you are trying to do the same motion profiles in both that seems a bit unlikely. On the other hand I have not compared BRX to CTRIO instructions, so maybe not completely unlikely)

What sort of frequency are you operating at ? and what kind and length are your data cables?

I noticed that the BRX discrete output specifications have a: "Maximum Switching Frequency 1m cable 250kHz, 10m cable 100kHz " also a maximum current of 0.5A

on the other hand the CTRIO2 has a max current of 1A and I found no cable length restriction in my skimming of the manual.

Now you may think your what, 10mA? current to the diver is so far below even 0.5A it can't make any difference, but high frequencies can be weird. Personally the first thing I'd do is put a 'scope across the drive and make sure I had something that looks like a square wave (One can get a pretty decent import 'scope for the price of a CTRIO2)

Created Date: September 22,2017

Created by: automa

I have my scope loaded in the truck to take in tomorrow to see if i can find anything. It is undoubtedly a programming issue. Cables are about 5ft long, shielded twisted pair 18 awg. I have tried various frequencies from 100hz to ~5khz with the same results. The hardware is identical to the other setups running these steppers with the exception of the BRX. Thanks Bobo, I will email the program in the morning.

Created Date: September 22,2017

Created by: Adisharr

Of course a common reason of non-repeatable motion in stepper systems is the open loop motor missing steps due to various mechanical problems, but the fact that the system works with the CTRIO conveniently eliminates that whole branch of potential issues (well, probably, there could conceivably be resonance issues due differences in ramp generation, but if you are trying to do the same motion profiles in both that seems a bit unlikely. On the other hand I have not compared BRX to CTRIO instructions, so maybe not completely unlikely)

What sort of frequency are you operating at ? and what kind and length are your data cables?

I noticed that the BRX discrete output specifications have a: "Maximum Switching Frequency 1m cable 250kHz, 10m cable 100kHz " also a maximum current of 0.5A

on the other hand the CTRIO2 has a max current of 1A and I found no cable length restriction in my skimming of the manual.

Now you may think your what, 10mA? current to the diver is so far below even 0.5A it can't make any difference, but high frequencies can be weird. Personally the first thing I'd do is put a 'scope across the drive and make sure I had something that looks like a square wave (One can get a pretty decent import 'scope for the price of a CTRIO2)

I second this, I 've seen a couple applications where misshapen output pulses was the problem.