User Manual

PD42-1141 TMCL
™
Firmware Manual • Firmware Version V1.42 | Document Revision V1.06 • 2018-JAN-09
91 / 109
6.1.3 How to choose Pulse Divisor and Ramp Divisor
The pulse divisor should be choosen in such a way that the range of the velocity internal units (0. . . 2047)
covers the entire velocity range which is needed by the application. Ideally, set the pulse divisor so that the
maximum velocity value of 2047 leads to a velocity that is just little but not much above the maximum
velocity needed by your application. This way it is possible to make optimum use of the internal velocity
resolution. The same is true for the acceleration and the ramp divisor.
The difference between ramp divisor and pulse divisor may limit the usable acceleration range for posi-
tioning ramps (MVP command), but not for velocity mode (ROL/ROR command). These limits are given by
the following equations:
a
lower_limit
= 2
ramp_div−pulse_div−1
a
upper_limit
= 2
ramp_div−pulse_div+12
− 1
If a
upper_limit
should be greater than 2047 then the upper limit is 2047.
6.1.4 Conversion between PPS, RPM and RPS
In order to convert between pps units and units like rounds per second (rps) or rounds per minute (rpm),
one has to know the fullstep resolution of the motor (full steps per round) and the microstep resolution
setting of the module (axis parameter #140, default setting is 256 microsteps per full step).
So to convert from pps to rps, use the following formula:
v
rps
=
v
pps
r
fullstep
· r
microstep
To convert from rps to rpm, use:
v
rpm
= v
rps
· 60
With the following symbols:
• v
rps
: velocity in rounds per second
• v
rpm
: velocity in rounds per minute
• v
pps
: velocity in pulses (microsteps) per second
• r
fullstep
: fullstep resolution of the motor (with most motors 200 (1.8°))
• r
microstep
: microstep setting of the module (default 256)
So, with a 200 fullsteps motor and a microstep setting of 256 (axis parameter #140 = 8), a velocity of
51200pps will result in 1rps (60rpm).
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