750-671 [Steppercontroller]
•
75
Configuration
WAGO-I/O-SYSTEM 750
I/O Modules
2.1.2.10.7.1.2
Travel
The travel, or path, is measured in "steps". The number range is 24 bits,
including sign.
Position range: -8388608 ... +8388607,
Presentation in two's complement.
2.1.2.10.7.1.3
Velocity
Velocity is measured in "steps per unit of time", with the range being ±15 bits.
Velocity range:
Velocity
min
... Velocity
max
= -25000 ... +25000.
The maximum pulse rate is 500000 Hz. This frequency is derived from an
internal 2 MHz cycle by a prescaler.
Parameters can be assigned to the prescaler, with the permissible range being
Freq_Prescaler = 4 ... 65535.
The maximum pulse rate f
max
is calculated by:
f
max
= 25000 / (12.5 ms * Freq_Prescaler)
= 2 MHz / Freq_Prescaler
= 500000 Hz … 30.5 Hz
Resolution = 1 / (12.5 ms * Freq_Prescaler)
= 80 Hz / Freq_Prescaler
= 20 Hz … 1.2 mHz
Freq_Prescaler f
max
: maximum
velocity/frequency
Frequency
resolution
4
500000 Hz
20 Hz
80
25000 Hz
1 Hz
65535
30,5 Hz
1.2 mHz
To ensure the highest degree of accuracy, the value Freq_Prescaler should be
set for the smallest whole value at the greatest speed required by the motor.
For example, if a stepper motor is to operate at 200 steps and 64 microsteps at
speeds between 0 … 20 s
-1
, a Freq_Prescaler range of 4 ... 7 is possible. A
setting of Freq_Prescaler = 7 provides the highest degree of accuracy and
frequency resolution.
