Longest axis move possible?

JD

We have a duet2 v1.04c that I think we were operating the 3.2 firmware with. We have a single stepper motor that we just wanted to command to turn for 3 or more hours. It's not part of a cnc or 3d printer. The motor doesn't use any endstop. I didn't check the microsteps setting in the config but i suspect we're operating at 1/16 or 1/8th?
After G1 commanding the stepper motor to rotate for three hours from a gcode file, the system seemed as if it stopped rotating 20 or so minutes shy of the 3 hours and subsequent commands of the gcode file did not execute. The movement number was about 10200 and the feedrate was about 60.2
With the M114 command, we see that the microstep count is quite high (over 1000000?) after half an hour. We see that when then commanding the motor to turn back in the other direction that the microstep count then decrements. We haven't had an issue if the rotate forward for a half hour and then back for a half hour and repeat. The axis count doesnt move - i presume because the axis never gets homed. Is there a maximum microstep count? what is expected if the max count is reached or exceeded?
Thanks in advance, JD

dc42

@jd the microstep count is a 32-bit signed integer. Therefore the longest move possible is (2^31 - 1) microsteps.

achrn

@dc42

I'm possibly about to do something similar (in my case long duration moves on a continuous rotation axis, which has 115,200 microsteps per rev, at 5 secs/rev, 2^31 is 'only' 26 hours of rotation). That's probably enough, actually, but I'd like to know how close I will be to the limit.

Is the microstep count reset after each move, or does it accumulate through the duration of a single print job? That is, is each move limited to finishing within +/- 2^31-1 steps from the start of that individual move, or does the whole print job have to remain within +/- 2^31-1 steps from the starting point?

If it is the latter, can the counter be reset, i.e. is there a gcode that causes a zero-the-microsteps counter (perhaps as a side effect of something)?

dc42

@achrn the microstep counter accumulates. A G92 command will reset it.