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Interrupt Processing
9.4.4
Notes on the Characteristics of Inputs and Outputs
The inputs and outputs of the module require an external load power supply.
The load current of all inputs and of output byte "x" is supplied through L1+.
The load current of output byte "x+1" is supplied through L2+.
The LEDs for the inputs and outputs are driven from the 5 V side of module.
This results in the following:
•
An input signal is only detected and indicated via LED if the PLC power supply is switched on
and the load voltage L1+ (at pin 36) is switched on.
•
Output LEDs can indicate signal status 1 even if 24 V are not applied to the output. This is the
case when there is no load voltage supply or if an output has short-circuited.
Note
If L1+ fails, the inputs are read in as logic "0" and the LEDs are switched off.
There is electronic short-circuit protection for the outputs. The maximum value of the tolerance-
dependent switch-off current is 3.6 A. There is no overload protection if an output is operated in
the range between 1.5 A (nominal value) and the maximum switch-off current.
You must ensure that in the event of cable short-circuit, the maximum switch-off current is
exceeded. This can be done either by selecting suitable cable cross sections or by limiting the cable
length.
9-18
S5-115U Manual
EWA 4NEB 811 6130-02b
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