Re: flying axis...

["Keith Rumley" <dscadcam-at-yahoo.com>]

Enrique,

>From /emc/src/rs274ngc/rs274ngc.hh:
    #define RS274NGC_OK 0
    #define RS274NGC_ERROR -1
    #define RS274NGC_EXIT 1
    #define RS274NGC_ENDFILE 2
    #define RS274NGC_EXECUTE_FINISH 3

>Issuing EMC_TASK_PLAN_EXECUTE --         (+509,+268,    +2,g21,)
>emcTaskPlanExecute(g21) returned 0

>From the log it shows that the task is returning 0 from the G21
initialization. From that it seems the EMC tasks/interpreter is functioning
correctly.

>  when I turn the machine on, after a few seconds the output voltage
> goes from 0 to 9.98 volts without issuing any command...

Sounds like the position loop is trying to stabilize. Two things come to
mind.
1. Possible causes of motion intitiation:
  encoder fault/line noise, causing EMC to think a motor is moving.(most
likely, as EMC doesn't initiate motion at startup)
  deadband setting (motor trying to hold an impossible position value -
0.00001mm, etc.)
2. Over-correction by PID loop
  encoder ratio
  encoder polarity in the emc.ini , as set by sign of the ratio value
( -/+20480, for example)
  direction settings in your driver/amp (may be correctable by the encoder
polarity setting)
  unstable PID settings (try values from a similar axis, lower is better as
starting point)
  loose or faulty connections (try swapping x & y axis connectors at the
motor/encoders, for example)

In my case, the servo drives have a software code for direction set.
(Emerson)

For good measure, you may want to check the RS274NGC_STARTUP_CODE in your
emc.ini file, and the 5220 variable in emc.var (should be '1').

HTH
- Keith Rumley






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