Siemens S5-135U/155U appendix Supply for CC/EU and I/Os, Switching on, Switching off

Digital Input/Output Modules

With Enable Input Switched Off

Examples of

Functioning of the

Enable Inputs

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
	a)	Battery
	I/O Modules	b)
	F+
CC/EU	L+
24V Power Supply	L+
24 V DC

Enable supply from:

a)Battery

b)Terminals for 24 V on the front plate of the power supply

8-6	System Manual
	C79000-G8576-C199-06