64
The number of pulses and the cycle time can be changed with
an interrupt. In the accompanying example, each pulse is initially
on for 500 ms and off for 500 ms. After four pulses, an interrupt
occurs which changes the cycle time to 2 seconds, 1 second on
and 1 second off.
500 ms
Interrupt
Occurs
1 sec 1 sec
Pulse Width Modulation The Pulse Width Modulation (PWM) function provides a
(PWM) fixed cycle time with a variable duty cycle. When the pulse
width is equal to the cycle time, the duty cycle is 100% and the
output is turned on continuously. In the following example, the
output initially has a 10% duty cycle (on 10%, off 90%). After an
interrupt, the output switches to a 50% duty cycle (on 50%, off
50%).
Interrupt
Occurs
10% Duty Cycle 50% Duty Cycle
On Off On Off
The PWM function can be used to provide a programmable
or adjustable control of machine timing. This allows machine
operation to be varied to compensate for product variations or
mechanical wear.
And Much More The instructions listed in this section are only examples of
the types of instructions available for S7-200 PLCs. The full
instruction set includes a much broader range of capabilities.
Refer to the S7-200 System Manual for additional information.
To Next Page
Loading...
