Siemens S5-135U/155U - Manual (Page 318)

8-6
System Manual
C79000-G8576-C199-06
Jumper inserted: Enable input (F+/F-) active (factory setting)
Jumper open: Enable input (F+/F-) switched off
If removal and insertion of modules during operation is not required, you
must remove the plug-in jumper for changeover of the enable mode. Wiring
of the enable inputs (F+/F-) can then be dispensed with.
Almost power-free shutdown of individual subprocesses, i.e. outputs of
various modules can be operated from a common load supply and yet
activated separately.
The load voltage of each individual module can be monitored without
additional circuitry. Any reactions to failure of the load voltage can be
programmed in the QVZ (timeout) organization block.
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 in-
puts of the I/O modules must still be present as long as voltage is
applied to the CC/EU.
You should observe the following instructions for switching off PLCs and
equipment for supplying power to the enable inputs:
24 V supply for CC/EU and I/Os
F+
L+
I/O Modules
24 V DC
b)
a)
CC/EU
L+
Battery
24V Power Supply
Enable supply from:
a) Battery
b) Terminals for 24 V on the front plate of the power supply
With Enable Input
Switched Off
Examples of
Functioning of the
Enable Inputs
Digital Input/Output Modules