Siemens S5-135U/155U System Manual page 419

Configuring
You must observe the following when configuring systems:
Switching on
Switching off When the PLC has been switched off, the voltage at the
Switching off the You should observe the following instructions for switching off CCs and
CC
equipment for supplying power to the enable inputs.
Separate or
When there is a need to switch off the load power supply separately without
Common
affecting the enabling of modules, there are the following possibilities for
Shutdown of the
producing the enable voltage. These exist even when the load power supply
CC/EU and Load
is used without an additional capacitor and common shutdown.
Power Supply
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
System Manual
C79000-G8576-C199-06
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.
enable inputs of the I/O modules must still be present as
long as the internal 5 V voltage is present.
230 V AC supply for CC/EU and load power supply
a)
–951
Power Supply
230 V AC
Load Power Supply 24V
Analog Input/Output Modules
b)
I/O Modules
F+
CC/EU
L+
L+
Battery
c)
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