Mesa 5i25+7i77 plug-n-go configuration

Yes the drives signal gnd can be returned to TB5 pin 3 (analog gnd) with a separate wire
also, there should be no explicit connection of any field I/O pin to the analog signals so
the field power gnd connection should be removed

I checked the voltage at TB5 from pin 3 to pin 4. (with all TB5 wires disconnected)

I get 1.1volt with Linux off.

I have the 5v supplied at Tb1 from the 5i25, that is currently showing 4.8.

My interpretation of your statement is that the 1.1volt reading indicates a bad board? because we would expect to get zero at this location.

I checked the 3&4 pins of other axis and I get a similar reading approx. 1.1volts

Is it time to order a new board?


fixing the signal ground to pin 3 instead of field ground had no effect

I would request a RMA number from Mesa for the 7I77 and when you get the number,
send the 7I77 back to Mesa for evaluation, repair and possible replacement

33zy: we have received and repaired and returned your 7I77
Since I dont have any contact information I will post this here

The problem found was a bad 74ACT04, This likely indicates
that the7I77s 5V supply was wrong (Either backwards or >7V)
So please check your power supplies before re-installing the 7I77

Thank you very much for your assistance. We received the boards. After checking field power 24v and using the 5i25 5v, we have reinstalled.

When I hit the soft enable, the drive enables and waits for a command. This is good progress.

When I manually jog the machine, I now get a following error as it appears to run away. I increased the ferror to 1.0 in an effort to better understand.
I am assuming I need to tune the drives?
Is their a recommended process for tuning the drives?

Thankyou

John Thornton has a webpage tutorial he put together on servo tuning, this might help:

gnipsel.com/linuxcnc/tuning/index.html

I picked it off one of these forum topics.

If the encoder readings are in the correct direction and scaled properly,
and you get a servo runaway, you will have to reverse the output polarity in the hal file

"Set encoder scale Use the machine data to calculate the number of encoder counts per inch (or mm). For example, if your machine has 5 turn per inch ballscrews, a 40 tooth timing belt pulley on the leadscrew, a 20 tooth pulley on the motor, and a 512 cycle per revolution (2048 count per revolution) encoder, the scale is 5 turns per inch * ( 40 teeth on screw / 20 teeth on motor ) * 2048 counts/rev = 20480 counts per inch. The position-scale parameter of the encoder HAL block should therefore be 20480. Once you set the scale parameter, then the 'position' HAL pin shows the axis position in inches (or mm). "

from the ini file
INPUT_SCALE = 20480
OUTPUT_SCALE = -1.000

corresponding to the HAL line

# encoder feedback
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.scale [AXIS_0]INPUT_SCALE

# position command signals
setp hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout0-scalemax [AXIS_0]OUTPUT_SCALE

Am I misinterpreting the tutorial line above?
When the tutorial refers to the "position HAL pin" how can I figure out which on that is?

Thank you

if you move the axis (with the drives disabled)
is the encoder scaling and direction correct?

(as read on the axis DRO and verified against a dial indicator, caliper or some other position reference)

table direction and deflection verified against Linux display and correct. Sorry for that distraction.

When I soft enable Linux, all is well.
Then I hit jog (.1).
The machine jogs in the correct direction followed by brief pause and it then runs away 5 to 8 inches to the right with a following error.


Back to tuning. I have been reading about setting base period and servo period. I only see servo period in the ini, is that OK? Am I missing base period?

I started with this (ini & hal) files as a baseline because the config didn't have a config for 7i77/5i25/servo, so I am cautious that I could have started from a poor entry point.

[EMCMOT]

EMCMOT = motmod

# Timeout for comm to emcmot, in seconds
COMM_TIMEOUT = 1.0

# Interval between tries to emcmot, in seconds
COMM_WAIT = 0.010

# Servo task period, in nanoseconds
SERVO_PERIOD = 1000000


# PID tuning params
DEADBAND = 0.000015
P = 100.0
I = 0.000
D = 0.000
FF0 = 0.000
FF1 = 1.000
FF2 = 0.0
BIAS = 0.000