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Siemens S5-135U/155U User Manual

Page 419

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9-37

System Manual
C79000-G8576-C199-06

You must observe the following when configuring systems:

Switching on

At the latest 100 ms after power-up of the PLC, the voltage
must be present at the enable inputs of the I/O modules.

Switching off

When the PLC has been switched off, the voltage at the
enable inputs of the I/O modules must still be present as
long as the internal 5 V voltage is present.

You should observe the following instructions for switching off CCs and
equipment for supplying power to the enable inputs.

When there is a need to switch off the load power supply separately without
affecting the enabling of modules, there are the following possibilities for
producing the enable voltage. These exist even when the load power supply
is used without an additional capacitor and common shutdown.

S

230 V AC supply for CC/EU and load power supply

F+

L+

I/O Modules

230 V AC

CC/EU

–951

a)

c)

b)

Battery

L+

Power Supply

Load Power Supply 24V

Supply for the enable inputs from:
a) 6ES5 951-4LB11 load power supply
b) Battery
c) Terminals for 24 V on the front plate of the power supply

Configuring

Switching off the
CC

Separate or
Common
Shutdown of the
CC/EU and Load
Power Supply

Analog Input/Output Modules