When the motor is creeping and the encoder is "seen to count", does the controller actually show the position register (TP) consistently increasing, or is it just changing around the same value?

If it is consistently increasing then also check RP, TE and TT.

If TP is not increasing, but changing around the same value, then you most likely are getting noise on your encoder lines.

Andy, thanks for the swift reply.

I haven't checked TP in smartterm, but is it TP that is shown in the encoder input fields in galiltools? The encoder value here gradually creeps up or down in what seems to be a linear fashion, as if it were doing a slow jog, at perhaps 1-5mm per min. If left alone, it continues and eventually hits a limit switch. It stops if the ampen input is off.

You can issue the TP command in GalilTools as well. _TP(axis) is shown in the watch window.

What about RP, TE and TT?

I'll have a look at RP, TE and TT tomorrow when I'm back in the workshop (and looked up what they are!)
thanks

Hi Andy,

I took a look at the machine today, forgive me for my ignorance of the Galil command set at present, but here's what I did:

controller on, GalilTools open (no other apps open on PC)

in terminal, entered:
MO (all encoder windows display static value in GalilTools)
SHA (encoder window for A axis only immediately starts increasing, around 150 counts/sec, motor is turning)
TPA=?
0.00
RPA=?
0.00
TEA=?
0.00
TTA=?
0.00
MO (count ceases)

does this shed any light on the issue?

I balanced out the creep yesterday on the amps, but they are creeping again today.

take out the "=?" on all of the commands. So just TPA, RPA, TEA, TTA.

These commands a queries, so =? is not needed. That is only used on commands that are used to set values. For instance with the KP command, you would issue KPA=?.

Actually, use this command:
MG_TPA,_RPA,_TEA,_TTA

Issue it about once every 5-10 seconds 5 times, post the commands and responses.

I knew I'd get an opportunity to demonstrate my ignorance, I just didn't think it'd happen so quickly!

I'll do that tomorrow (it's 9pm here now..)

thanks again

I tried that today, these are the results from approx 5 sec intervals:

MG_TPA,_RPA,_TEA,_TTA
-42962.0000, 0.0000, 42962.0000, 0.0000
MG_TPA,_RPA,_TEA,_TTA
-43181.0000, 0.0000, 43181.0000, 0.0000
MG_TPA,_RPA,_TEA,_TTA
-43360.0000, 0.0000, 43360.0000, 0.0000
MG_TPA,_RPA,_TEA,_TTA
-43555.0000, 0.0000, 43555.0000, 0.0000
MG_TPA,_RPA,_TEA,_TTA
-43792.0000, 0.0000, 43792.0000, 0.0000

do these point to anything?

_TTA is showing that the controller is not trying to compensate for the error (_TEA). This means that either you have the PID's set to 0, or the controller has shut of the motor and you do not have the amplifier enable wired. Check your KP, KD and KI values, and your amplifier enable wiring.

thanks Andy, I do actually have KD and KI set to 0. I've just tried tuning the motors again (including using the autotune feature in GalilTools), and I get oscillations if KD is anything above 1. If KD=1 I can just about get it so that each axis is stable (and doesn't creep!) but when I jog, they overshoot by quite a distance and have to correct. The motors/drives/mechanical drivechain are all as per the factory machine spec, all I've done is replace the PLC with the Galil. Any ideas?

Steve,

E-mail support@galilmc.com and reference this post.

just to follow up on this thread, it turned out that my amps were set to velocity mode- I eventually got hold of a manual for them from Italy, and now I'm running them in torque mode, the autotune works a lot better, so I've got some KP and KI now without mad oscillation. I think they were trying to correct errors themselves, but now the Galil does it. Thanks for the help.