Siemens SIMATIC ET 200SP Manual page 28

Modes and Functions
3.3 Pulse width modulation (PWM) mode
Note
If Dithering is activated without current control, then the minimum pulse duration and
minimum inter-pulse period are used by the module. In this case, the superimposed
Dithering is reduced so the effective pulse duration fits in the allowed range.
Setting and changing the pulse duty cycle
OUTPUT_VALUE assigns the duty cycle for the current period duration. You select the
range of the OUTPUT_VALUE control interface field with the "Output format" parameter.
● "Per 100 (%)" output format: Value range between 0 and 100
Pulse duration = (OUTPUT_VALUE/100) x period duration.
● "Per 1,000 (‰)" output format: Value range between 0 and 1,000
Pulse duration = (OUTPUT_VALUE/1,000) x period duration.
● "Per 10,000" output format: Value range between 0 and 10,000
Pulse duration = (OUTPUT_VALUE/10,000) x period duration.
● "S7 analog output" output format: Value range between 0 and 27,648
Pulse duration = (OUTPUT_VALUE/27,648) x period duration.
You assign OUTPUT_VALUE directly with your control program. A new OUTPUT_VALUE is
applied at the next rising edge of the output.
When the current control option is enabled, the TM Pulse 2x24V module takes control of the
duty cycle and the OUTPUT_VALUE control interface field is used to assign the target
current as a ratio of target current/reference current. See the Current control (Page 78)
function for details.
Setting and changing the period duration
● Permanent update
The period duration is controlled permanently using the control interface. The
MODE_SLOT bit has to be set ("1" means permanent update); LD_SLOT has to have the
value 1 ("1" means Period duration).
Set the period value in the field SLOT. The unit is always microseconds.
– High-speed output enabled: between 10 μs and 85,000,000 μs in the field SLOT.
– High- speed output disabled: between 100 μs and 85,000,000 μs in the field SLOT.
● Single Update
Set the period duration in the configuration parameters. Alternatively, perform a single
update using the control interface. MODE_SLOT has to be cleared ("0" means single-
update); LD_SLOT has to have the value 1 ('1' means Period duration). Set the period
duration value in the field SLOT. The unit is always microseconds.
– High-speed output enabled: between 10 μs and 85,000,000 μs in the parameters.
– High-speed output disabled: between 100 μs and 85,000,000 μs in the parameters.
The new period duration is applied with the next rising edge of the output.
28
Technology module TM Pulse 2x24V (6ES7138‑6DB00‑0BB1)
Manual, 09/2015, A5E35061186-AA