current values and status information from the high speed
counter via the feedback interface.
Note
Operation with High_Speed_Counter technology object
The High_Speed_Counter technology object is available for high-speed counting mode. We
therefore recommend use of the technology object High_Speed_Counter instead of the
control interface/feedback interface for controlling the high speed counter.
For information on configuring the technology object and programming the associated
instruction, refer to the , ET 200MP, ET 200SP Counting, measurement and positionThe pulse-width modulation (PWM) mode of the compact CPU has the following technical
properties:
Minimum Maximum) A lower value is theoretically possible but, depending on the connected load, the output voltage can no longer be output
as complete rectangular pulse
2) Load dependenWith pulse width modulation, a signal with defined cycle duration and variable on-load factor
is output at the digital output. The on-load factor is the relationship of the pulse duration to
the cycle duration. In PWM mode, you can control the on-load factor and the cycle duration.
With pulse width modulation you vary the mean value of the output voltage. Depending on
the connected load, you can control the load current or the power with this.
You can specify the pulse duration as one-hundredth of the period duration (0 bis 100), as
one-thousandth (0 to 1000), as one ten-thousandth (0 to 10,000) or in S7 analog format.Period duration
② Pulse duration
The pulse duration can be between 0 (no pulse, always off) and full-scale deflection (no
pulse, period duration always on).
The PWM output can, for example, be used to control the speed of a motor from standstill to
full speed or you can use it to control the position of a valve from closed to completely open.
You configure the pulse width modulation (PWM) mode in STEP 7 (TIA Portal).
The pulse width modulation mode has the following functions:
● When the option "High-speed output (0.1 A)" is activated, you can generate a minimum
pulse duration of 2 μs at a current of 100 mA. If the option "High-speed output (0.1 A)" is
not activated, you can generate a minimum pulse duration of 20 μs with a load > 0.1 A
and a minimum pulse duration of 40 μs with a load of ≥ 2 mA and a current of maximum
0.5 A. If a standard output is used, you can generate a minimum pulse duration of 100 µs
with a load of > 0.1 and a minimum pulse duration of 200 µs with a load of ≥ 2 mA.
● You can control the pulse output (DQA) of the channel manually via the control and
feedback interface.
● You can configure the reaction to CPU STOP. Upon change to CPU STOP, the pulse
output (DQA) is set to the configured stateFor 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 169)
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. 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.• If TM_CTRL_DQ = 1, the technology function takes over the control and generates pulse
sequences at the output PWM DQA.