wtw DIQ/S 181, Operating Manual, Page: 70 / 104

Outputs
DIQ/S 181
70
ba77083e01 02/2015
Pulse width output The output via the pulse width is used, e.g. for controlling valves.
Pulse-width regulation changes the duration of operation (t
on
) of the
output signal. Depending on the position of the measured value in the
proportional range, the relay is operated for a longer or shorter period.
Fig. 6-4 Relay output of the pulse-width output
The cycle duration (T) is made up of the turn-on and turn-off switching
duration (t
on
, t
off
) of the relay together. While the selected cycle durati-
on (T) remains constant, the turn-on duration (t
on
) changes depending
on the measured value and, with it, the pulse width (v). The pulse width
can be set from 0 % to 100 %.
v = (t
on
/ T) * 100 %
v = pulse width, T = cycle duration, t
on
= turn-on duration

If the measured value is at the end of the proportional range ( End
value ), the turn-on duration (t
on
) is long, the turn-off duration is short.
This means the relay operates for a longer period.

If the measured value is at the beginning of the proportional range
(
Start value ), the turn-on duration (t
on
) is short, and the relay
operates for a correspondingly shorter period.
1 Start value
Measured value with a minimum pulse width or switching
frequency
2 End value
Measured value with a maximum pulse width or switching
frequency
If the duration of the closing or opening pulse is shorter
than 0.1 s, the relay remains open or closed for the
complete cycle duration.
T
Time [s]
Relay
Off
On
t
On
t
Off