General Help

Limited success today. Got the X axis servo and encoder working. Thry're going in the right directions and counting pulses.
However, when in PNCconf and after clicking on TEST and enabling amplifier, the servo begins to drift ever so slightly in one direction.
I've played around a little with the PID figures but nothing I do seems to remove or even increase the drift.
Initial figures are deafult: P=50, FF1=1

Tuning documentation says to increase P until loop becomes unstable (I'm assuming this means the axis oscillates in both directions ??) but increasing P doesn't seem to change anything.

Any thoughts???

How do I know if PID is enabled? (rookie question, I’m sure!)

Must confess I don’t really understand enough about the HAL side of all this - took me all day to get the halscope working!

So far I’ve been doing all my testing and tweaking through the PNCconf setup wizard, using the open loop encoder/servo rest. I read somewhere else in the forum today I can actually run some test through AXIS itself???

The key words in the pncconf test are "open loop", so drift is expected
you need to run a real configuration in axis (or other GUI) to actually tune your system
Do expect runaways when you start until you have the feedback direction correct so make sure
your drive enables are working and you hand is over the estop button/power switch

Sound advice!!
Ok, thanks very much for all the help so far.... keep you posted!

Hi all,
Have made some progress with servos and encoders on the X axis. Am trying to set up the limit switches. I've got them to deliver a signal correctly but now, when in Axis I can drive the table to the limit switch but then Axis stops and I can't back off the limit switch?
Is there some setting I have to check or do I need to edit the software?

OK thanks for that. I've noticed that the 'ignore limits' check box is greyed out though some of the time.

Am now trying to have a go at PID tuning. Have followed documentation and have got some signals on the halscope. However, when I go to jog the axis it seems to jump then smooth out. Can I count this jump as the 'oscillations' refered to in the documentation?

I have separate min and max limits, and still have to check the override limits to be able to jog off of one. It is a small check box on the left side of the screen. It is normally greyed out until you hit one of the limits.

andypugh wrote:

You should have an "ignore limits" check-box in the left-side section of the screen.

(If you have separate max and min limits set up I think that you are allowed to jog off the limit automatically, but if both limits share an input pin the system has no way to know which way is "off")

THANK YOU! That is really helpful info. I never noticed that checkbox because it was grayed out. Occasionally I get my Z stuck on the limit and I would jump the micro switch to get off of it.