Peter,

Thanks. That is basically what I thought. It has been reported to me that,
in a servo / encoder system, if EMC is shut down, then one or more axes are
moved and finally EMC is restarted, upon clearing the e-stop a runaway
condition occurs (at least sometimes). I have to get more information, but I
thought perhaps the Mesa board was holding onto the position information
while EMC was not running, and then once the e-stop is cleared, tries to
move to the initial position (i.e. 0,0,0).

Regards,
Eric


Loading the firmware will clear the encoder counts (the register values will
be loaded from the bitfile = 0), If you dont reload the firmware, the
hardware count will be correct, but since its only a 16 bit counter and
could have wrapped without the driver noticing, actual count read by the
driver could be wrong.

The driver may also clear the counter as part of its startup, no sure about
that.

If you wanted to maintain position info across EMS starts, a 24- 32 bit
counter would probably be needed. The 16 bit counter was used so that that
the timestamp and encoder count are read simultaneously in one 32 b it read
operation.




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