Standstill Condition - WAGO -I/O-SYSTEM 750 Manual

40 • 750-636 [DC Drive Controller]
Function Description
2.1.1.9.11

Standstill Condition

During the execution of the motion commands, the braking distance of the
drive is determined at every stop. The braking distance is covered when the
module detects the motor standstill via missing incremental encoder pulses.
Observation of the standstill is also done during an inactive drive cycle. In
both cases, the result is displayed in the module status of the process image.
Based on the information in section section 2.1.1.9.12, "Maximum Pulse
Frequency of the Incremental Encoder" regarding the maximum number of
pulses of the DC drive controller, the following illustration was created to
depict the revolution speed in pulses for different incremental encoders.
Fig. 2.1.1-28: Revolution speed in pulses
The incremental encoder with 4 pulses/rev generates approximately 7 pulses at
100 rev/min. This value (7 pulses) is now defined as the maximum limit value
for the standstill condition.
However, the lighter the axis load, the slower the motor in PWM mode can
turn. In order to provide a more sensitive setting to fulfill the standstill
condition, even with lighter axis load, the limit value can be configured using
values smaller than 1 pulse.
Regarding positioning quality, smaller limit values lead to smaller positioning
errors (especially with a large centrifugal mass or encoders that have a higher
resolution), but also to a longer total time for the positioning operation.
p036305e
WAGO-I/O-SYSTEM 750
I/O-Modules