Design; Function Of The Enable Inputs - Siemens S5-155U System Manual

Technical Description
8.1.1

Design

LED indicators
Addressing switch
8.1.2
Function of the Enable
Inputs
8 - 6
The modules are designed as plug-in PCBs for central controllers and
expansion units with backplane connector and with a blade connector
to accept a plug-in front connector. The front connector has screw or
crimp terminals and is available separately; you can connect the
process signal lines to it directly.
Fitted to each module is a strip with green LEDs to indicate the logic
states of inputs or outputs. The LEDs are arranged in bytes and
marked bit 0 to 7.
Output modules for direct voltage additionally have red LEDs to
indicate short-circuits between output lines and ground (L-) within a
group. Output modules for alternating voltage have red LEDs to
indicate a fuse failure.
Fitted on each module is an addressing switch with six, seven or eight
rockers to set the module address.
The modules are protected on both sides by covers.
Blade
Connector
Front
Connector
Figure 8-1 Digital Input Module
The digital input/output modules have an enable circuit. You can use
the enable inputs to implement electrical interlocks for certain
modules or switch off individual modules, whilst the PLC is in
operation.
Addressing Switch
LEDs
System Manual
C79000-B8576-C199-03