February 2012 11 – 145
11.7.4 PLC outputs
Output signals and
addresses
The switching outputs are transistor outputs with current limitation.
Please note:
PLD-H: The outputs are short-circuit proof.
Permissible load: Resistive load (ohmic load)
Inductive loads (e.g. relay, contactor) with an energy content of up to 100 mJ do not require a
quenching diode. If the energy content exceeds 100 mJ: only with quenching diode parallel to
inductance. Pay attention to the manufacturer's specification of the energy content when selecting
the switching devices.
If an output is operated with an inductive load without a quenching diode and is read back to an input,
the input must be protected by varistors or RC circuits.
For component-related reasons, the switching outputs should be loaded with at least 5 mA in "1"
state. They conform to EN 61131-2. If a resistive load consumes less than 5 mA, it is necessary
to insert, e.g., a relay.
For component-related reasons, a current of I
Off
= 500 µA flows through the switching outputs also
in "0" state. If high-impedance loads with a low-level lower switching threshold are connected
directly to the output, the voltage drop can lead to a "1" state. In such a case, a shunt resistor must
be connected to the output.
Output signals:
Number of digital outputs:
Supply voltage
for PLC outputs
See “Supply voltage for PLC outputs” on page 18 – 274.
PLD-H, UEC 11x, X9 of PL 62xx, and
machine operating panel
Min. output voltage for "1" signal 3 V below supply voltage
PLC outputs must neither be connected to a 24-V supply, nor to other PLC outputs with a
difference in potential. Otherwise, the voltage present at the PLC outputs is transmitted to
the power supply. As a result, the PLC outputs that can be switched off may nevertheless be
supplied with this voltage.
This could lead to damage or injury to property or persons!
Device Digital outputs
UEC 11x 23
PLD-H 16-08-00 8
PLD-H 08-16-00 16
MB 620 8
PLB 62xx (safety-related) 7
Maximum of 8 external PLC input/output systems (PLB 6xxx) are allowed in the HSCI system,
and of these, one system PLB 62xx or one UEC 11x.
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