76 •
750-671 [Steppercontroller]
Configuration
WAGO-I/O-SYSTEM
750
I/O
Modules
Freq_Prescaler = 2000000 Hz / f
max
with f
max
= Speed * Number of steps * Microsteps = n * Z * M yields:
Freq_Prescaler = 2000000 Hz / (n * Z * M)
= 2000000 / (20 * 200 * 64) = 7.8125
At this selected Freq_Prescaler, the module can output a maximum pulse
frequency of 285714.29 Hz at a setpoint of 0 … 25000, which corresponds to
a motor speed of 22.32 Hz. For a specified speed of exactly 20 Hz, a setpoint
of
Velocity = (f / f
max
) * Velocity_max = (n * Z * M / fmax) *25000
= (n * Z * M / (2000000 / Freq_Prescaler)) *25000
= 20 Hz * 200 * 64 * 7 * 25000 / 2000000 = 22400
must be specified in the process image.
Alternatively, an attempt can also be made to achieve a decadic relationship
between the setting and the motor speed by selecting a different
Freq_Prescaler. For example, Freq_Prescaler could also be selected as 6, in
which case the module could output a maximum pulse frequency of 333333,3
Hz at a setpoint of 0 … 25000, which corresponds to a motor speed of 26,04
Hz. For a speed of 20 Hz a setpoint of
20 Hz * 200 * 64 * 6 * 25000 / 2000000 = 19200 <~> 20000 – 4 %
must be specified. Here, the setting is nearly 100 times the motor speed.
At a setting of Freq_Prescaler = 80, the numerical speed value is equal to the
output frequency in [Hz].
These values can also be specified using user-specific units that can be
defined. For this, the specified data for speed is multiplied by a factor
Speed_Mult prior to internal processing and then divided by a factor
Speed_Div. If the internal
external or external
internal conversion
violates the permissible value range, the error message
1513 (UNITS_SPEED_INT_RESULT) or
1514 (UNITS_SPEED_USER_RESULT) is issued.
