Siemens S5-135U/155U appendix Timeout QVZ occurs in the CC, Switching off the Enable Input

Analog Input/Output Modules

Enable Input	The enable circuit requires an external 24 V voltage at enable inputs F+/F- in
	the front connector. If there is no voltage at F+/F-, the modules will not
	acknowledge.
	When the front connector is swivelled away from the front strip of the
	module, the supply of power to the enable input is interrupted, i.e. the
	module is switched off and can no longer be addressed by the user program: a
	timeout (QVZ) occurs in the CC.

Switching off the Enable Input

The -4Ux12 type modules additionally offer the facility for changing the enable mode. The modules have a jumper accessible from above in the vicinity of the addressing switch.

Enable Jumper

Figure 9-13 Enable Input and Enable Jumper

Jumper inserted:	Enable input (F+/F-) active (factory setting)
Jumper open:	Enable input (F+/F-) switched off

Examples of functioning of the enable inputs:

STo switch off individual subprocesses, i.e. outputs of various modules can be operated from a common load supply and yet activated separately.

SThe load voltage of individual modules can be monitored without additional circuitry. Any reactions to failure of the load voltage can be programmed in the QVZ (timeout) organization block.

9-36	System Manual
	C79000-G8576-C199-06