Siemens Simatic S7-1500 CPU 1512C-1 PN - Page 53

Technology functions
3.2 Pulse generators
CPU 1512C-1 PN (6ES7512-1CK01-0AB0)
Manual, 12/2017, A5E40898741-AA
53
Controller
For the pulse width modulation (PWM) mode, the user program directly accesses the control
and feedback interface of the channel.
A reconfiguration via the instructions WRREC/RDREC and parameter assignment data
record 128 is supported. You can find additional information in section Parameter data
records (PWM) (Page 187)
You control the on-load factor (pulse
- cycle ratio) of the pulse width via the OUTPUT_VALUE
field of the control interface. Pulse width modulation generates continuous pulses based on
this value. The period duration is adjustable.
Figure 3-1 Pulse schematic
Starting the output sequence
The control program must output the enable for the output sequence with the help of the
software enable (SW_ENABLE 0 → 1). The feedback bit STS_SW_ENABLE indicates that
the software enable is pending at the PWM.
If the software enable is activated (rising edge), STS_ENABLE is set. The output sequence
runs continuously, as long as SW_ENABLE is set.
Note
Output control signal TM_CTRL_DQ
•
If TM_CTRL_DQ = 1, the technology function takes over the control and generates pulse
sequences at the output PWM DQA.
•
If TM_CTRL_DQ = 0, the user program takes over the control and the user can set the
output PWM DQA directly via the control bit SET_DQA.