Siemens S5-135U/155U - Manual (Page 433)

9-51
System Manual
C79000-G8576-C199-06
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.
The 465 module additionally offers the facility for changing the enable
mode. The module has a jumper accessible from above in the vicinity of the
addressing switch.
Enable Jumper
Figure 9-19 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:
S
To switch off individual subprocesses, i.e. outputs of various modules can
be operated from a common load supply and yet activated separately.
S
The 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.
Enable Input
Switching Off the
Enable Input
Analog Input/Output Modules