What is the maximum speed in microsteps per second of the POWERSTEP01 when in STEP mode. I am currently using x16 step mode. Also will motor move faster if I switch to x4 microstep mode.

[CBeif.1]

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[chaaalyy]

Of course it moves faster, if you switch to x4 instead of x16 ... x4 means 800 (Micro-)steps per rev, x16 3200. (Both with a standard stepper with 200 full steps / rev or in other words: 1.8 deg. step angle). To be honest: it nearly doesn´t matter, what max. step speed the powerstep01 understands... At fast speeds these steppers loose too much power (just physics...). Even with x16 mode and 3000 revs per minute (you can try, but you can stop the motor, running that speed, with a simple touch of your finger), this leads to a step frequency of just 160kHz, what shouldn´t be a problem for the powerstep01 (depending on your settings of course)