101BExtended instructions
8.6 Pulse
S7-1200 Programmable controller
290
System Manual, 11/2011, A5E02486680-05
Table 8- 121 Default output assignments for the pulse generators
Description
Pulse
Direction
Onboard CPU
Q0.0
Q0.1
PTO 1
Signal board
Q4.0
Q4.1
Onboard CPU
Q0.0
--
PWM 1
Signal board
Q4.0
--
Onboard CPU
Q0.2
Q0.3
PTO 2
Signal board
Q4.2
Q4.3
Onboard CPU
Q0.2
--
PWM 2
Signal board
Q4.2
--
8.6.3
Configuring a pulse channel for PWM
To prepare for PWM operation, first configure a pulse channel in the device configuration by
selecting the CPU, then Pulse Generator (PTO/PWM), and choose either PWM1 or PWM2.
Enable the pulse generator (check box). If a pulse generator is enabled, a unique default
name is assigned to this particular pulse generator. You can change this name by editing it
in the "Name:" edit box, but it must be a unique name. Names of enabled pulse generators
will become tags in the "constant" tag table, and will be available for use as the PWM
parameter of the CTRL_PWM instruction.
NOTICE
The maximum pulse frequency of the pulse output generators for the digital output is
100 KHz (for the CPU), 20 KHz (for a SB), or 200 KHz (for a high-speed SB). However,
STEP 7 does not alert you when you configure an axis that with a maximum speed or
frequency that exceeds this hardware limitation. This could cause problems with your
application, so always ensure that you do not exceed the maximum pulse frequency of the
hardware.
You have the option to rename the pulse generator, add a comment, and assign parameters
as follows:
●
Pulse generator used as follows: PWM or PTO (choose PWM)
●
Output source: onboard CPU or SB
●
Time base: milliseconds or microseconds
●
Pulse width format:
–
Hundredths (0 to 100)
–
Thousandths (0 to 1000)
–
Ten-thousandths (0 to 10000)
–
S7 analog format (0 to 27648)