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Chapter 7 Integrated OBs, SFBs and SFCs
SFC 225 HF_PWM
Description
Parameters
DO 8xDC24V 1A
L+
1
.0
2
.1
3
.2
4
.3
5
.4
6
Ch. 0
.5
7
.6
8
PWM
.7
9
F
I0
Ch. 1
7-16
This block serves the parameterization of the pulse duration modulation for
the last two output channels. This block is function identical to SFC 223.
Instead of timebase and period, the SFC 225 works with a predefined
frequency (up to 50kHz).
You define a frequency, the pulse duty ratio and min. pulse length. The
CPU determines an pulse series with an according pulse/break relation and
issues this via the according output channel.
The SFC returns a certain error code. You can see the concerning error
messages in the table at the following page.
The PWM parameters have the following relationship:
Output
DO
Pulse length
Pulse duty ratio
Period length = 1 / frequency
Pulse length = (period length / 1000) x pulse duty ratio
Pulse break = period length - pulse length
Period length
Pulse
break
500
700
1000
ADAM 8000 Manual CPU 821x – Rev 1.1
CPU ADAM 821x
11
21
51
x
x
x
Time
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