Pulse-Width Modulation Mode (Pwm) - Siemens SIMATIC ET 200S Operating Instructions Manual

5.3.3

Pulse-Width Modulation Mode (PWM)

Definition
You specify an output value to the 2PULSE. The 2PULSE generates continuous pulses on
this basis. The output value determines the pulse/interpulse ratio within a period (pulse-width
modulation). The period can be adjusted.
The pulse train is output on expiration of the assigned on-delay on the DO digital output of
the 2PULSE (output sequence).
Figure 5-5
Starting the Output Sequence
You must always issue the enable for the output sequence via a software enable
(SW_ENABLE 0→1; MANUAL_DO = 0) in your control program. The ACK_SW_ENABLE
feedback bit indicates the software enable pending at the 2PULSE.
You can also set the digital input DI of the 2PULSE as HW enable with the Function DI
parameter.
If you want to work with the software enable and hardware enable at the same time, when
the software enable has been issued, the output sequence starts with the first positive edge
of the hardware enable. Further positive edges of the hardware enable during the current
output sequence are ignored by the 2PULSE.
When the enable is issued (positive edge), the on-delay is started and the STS_ENABLE
set. The pulse train is output on expiration of the on-delay. The output sequence runs
continuously as long as SW_ENABLE is set.
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
Block Diagram for Pulse-Width Modulation Mode
2PULSE
5.3 Modes and Functions
265