Digital Output (Dq) - Siemens SIMATIC S5 IP 281 Equipment Manual

General Function Description
1.4.3

Digital Output (DQ)

Each counter is equipped with one, two-way, digital output with a nominal voltage of 24 V. The
digital output for counter 1 is available on plug connector X4; the digital output for counter 2 is
available on plug connector X6 (+ section 1.3.3).
The digital output can be used to directly trigger processes external to the module. The functions
of the diaital outRuts are described in section 6.7. Direct connection of a relay is possible (maxi-
mum Io[d current of 600 mA).
ing of DQ
Setting of the
minimum
Software
pulse
enable
duration
When activated, the output remains active for the minimum pulse duration. This minimum pulse
duration can be set to three different times (1Omsec/100 msec/500 msec) for each output indivi–
dually (+ section 2.3). If the triggering event lasts longer than the minimum pulse set, the output
remains active until the event has disappeared again.
The digital output is potentially isolated via optocouplers from the following.
– S5 bus
– Digital inputs
– 5.2 V encoder supply
The digital output is supplied by the 24 Vdirectvoltagefed by X3. A P switch is used as the output
driver. The digital output is short circuit proof and protected against overload.
The digital outputs are disabled after startup of the 1P 281. They are enabled by control register3.
The BASP signal is active during an interference, and during startup and stop of the PLC. The
applications require that the outputs not be switched off when an error occurs, the 1P 281 offers
the capability of switching off the BASP function for both digital outputs together (+ section 2.3).
Remember that, in such situations, the digital outputs are no longer protected by the safety system
of the SIMATIC S5.
When the BASP function is switched off, other suitable measures must be provided
to ensure that persons and systems are not endangered when the outputs are not
switched on.
20
1 –
24 V
— Driver
I
Status
R 11192
.
output
R
L
—
Free-
wheeling
diode