Pulse-Width Modulation (Pwm) - Siemens SIMATIC S7-1200 Manual

The timing diagram shows the operation of a CTD counter with an unsigned integer count
value (where PV = 3).
● If the value of parameter CV (current count value) is equal to or less than 0, the counter
● If the value of parameter LOAD changes from 0 to 1, the value at parameter PV (preset
Table 6- 19 CTUD (count up and down) counter
LAD / FBD SCL
"ctud_db".CTUD(
The timing diagram shows the operation of a CTUD counter with an unsigned integer count
value (where PV = 4).
● If the value of parameter CV (current count value) is equal to or greater than the value of
● If the value of parameter CV is less than or equal to zero, then the counter output
● If the value of parameter LOAD changes from 0 to 1, then the value at parameter PV is
● If the value of the reset parameter R is changes from 0 to 1, CV is reset to 0.
6.3.7

Pulse-width modulation (PWM)

Table 6- 20 CTRL_PWM instruction
LAD / FBD
Easy Book
Manual, 11/2011, A5E02486774-04
output parameter Q = 1.
value) is loaded to the counter as the new CV.
CU:=_bool_in,
CD:=_bool_in,
R:=_bool_in,
LOAD:=_bool_in,
PV:=_undef_in,
QU=>_bool_out,
QD=>_bool_out,
CV=>_undef_out);
parameter PV (preset value), then the counter output parameter QU = 1.
parameter QD = 1.
loaded to the counter as the new CV.
SCL
"ctrl_pwm_db"(
PWM:=_hw_pwm_in_,
enable:=_bool_in_,
busy=>_bool_out_,
status=>_word_out_);
6.3 Powerful instructions make programming easy
Operation
Desciption
The CTRL_PWM instruction provides a fixed cycle
time output with a variable duty cycle. The PWM
output runs continuously after being started at the
specified frequency (cycle time). The pulse width is
varied as required to affect the desired control.
Programming made easy
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