146 • I/O modules
Digital Outputs 750-511
Modular I/O System
ETHERNET TCP/IP
t
0V
24V
50%
t
0V
24V
0%
t
0V
24V
100%
t
0V
24V
25%
Fig.: 4-1 On/Off time relationships for Table 1.
Parameterizing the period/basic frequency
Either the period or the basic frequency can be predetermined any time by the
PLC via 2 writeable registers, which are not protected against voltage loss.
Register 2:
Period (16 bits)
Register 3:
Basic frequency (16 bits)
As soon as the basic frequency has been input, the period is calculated auto-
matically and entered in register 2.
The modification changes the frequency of both channels of the bus module.
The pulse width bus module loads the default values in the registers after
"power-on". The PLC must take this case into account if the required values
differ from the default values.
The correspondence between the digit value in the register and the period is
different for each type of bus module:
Item-No.
Frequency range
Period resolution
Basic frequency
resolution
750-511
250 Hz ... 20 kHz
1 µs / digit
1 Hz / digit
750-511/000-002
2 Hz ... 250 Hz
8 µs / digit
1 Hz / digit
Default Values:
Item-No.
Period
Value register 2
Basic frequency
750-511
4000 µs
4000 [0x0FA0]
250 Hz
750-511/000-002
10000 µs
1250 [0x04E2]
100 Hz