Mesa 5i20 with 7i40

Hello Gentlemen,

Once again, I show up as a lost ball in the high weeds seeking help. I have a new 2 axis controller set up using the Debian Live+Install with Mesa 5i20, 7i40H, and 7i37-TA boards. I used Pncconf to get going. All the I/O and the encoders work correctly. The 7i40 has a green (CR6) and a yellow (CR1) LED that are lit. It's also connected to a 60V power supply. If I tell either axis to Home of try to jog them, I get a joint following error. However, it doesn't appear that anything trys to move, and I don't get any kind of blip on my voltage meter across the motor leads.

Frank

Andy,

I've attached the HAL file. The enable pins are true when the machine is reset and switch with the following errors. The values never change from 0.

[AXIS_0]OUTPUT_SCALE --- 10
[AXIS_0]ENCODER_SCALE --- Correct
[AXIS_0]P --- 5
[AXIS_0]MAX_OUTPUT --- 10

I set my following errors to .5" to have more time before an error and the pwmgen values do change but they never go over .2. I still don't get a reading on the motor leads, even on the 200mv range.

firmware=hm2/5i20/SVST2_8.bit

By moving the P factor up to 15 I got the motors running.

Andy,

Thanks for your insight and help. I ended up with P=400 and all seems to be well. I've only tuned analog controllers before and anything above P=20 got unstable.

For bare Hbridge drives you typically need FF1 to compensate for the motors back-EMF
You adjust FF1 by doing long, high speed slews and zeroing the position lead/lag during
constant speed motion (I term must be 0 for this adjustment)

You will want as much D as you can get away with.
Once tuning is really close, you can add I term to eliminate static errors and reduce errors
at constant speeds.

You can typically get better performance (higher stable D and P terms) with Hbridges if you
increase the servo thread rate to 2 or 4 KHz (how high you can go depends on your CPU)