31.5.8.2 ON Duty
Value - PWM Output (LT Series)
ON duty value is the ON time and OFF time percentage in 1 pulse
and sets the ON time in percentage (%).
ON duty value effective range
As the output frequency becomes larger, the output waveform set
by the ON duty value becomes harder to realize. Therefore, when the
output frequency is large, set the setting effective range to
correct the output waveform.
How to calculate the effective range
Use the following formulas to calculate the high and low limits
of the ON duty effective range.
High limit: 100 - Hardware delay time *
(microseconds) × Output frequency
Low limit: Hardware delay time (microseconds) × Output
frequency
*The hardware delay time shows the total of ON→OFF (Time to
lower down to 2.4V, which is 10% of 24V) and OFF→ON (Time to rise
up to 21.6V, which is 90% of 24V). The hardware delay time of this
I/O board is 3 microseconds.
For example, when the hardware delay time is 3 microseconds and
the output frequency is 10000Hz
Upper limit:100 - 3 × 10-4 × 10000
= 97 (%)
Lower Limit: 3 × 10-4 × 10000 = 3 (%)
The ON duty effective range, therefore, is 3 to 97%.
-
Although you can set ON duty to 100% when
approximately 3 kHz or less, there is a gap of 1.6 microseconds in
each period when it's OFF, despite ON duty being 100%.
For example, for 500Hz, one period is 2 milliseconds during which
1.6 microseconds it's OFF.
Set Up Process in GP-Pro EX
From [System Settings], select [I/O Driver] and on the [Internal
Driver 1] screen, click [PWM Settings].
Specify from [ON Duty Value] in the [PWM Settings] dialog
box.
Set Up Process with System Variables
Define the ON duty value in the system variable (#L_PWM*_DTY).
The system variable name adjusts to match the CH pulse output to
which it's mapped.
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