Internal Electrical Configuration; Internal Electrical Configuration Of The S5-90U - Siemens SIMATIC S5-90U System Manual

S5-90U/S5-95U
2.2

Internal Electrical Configuration

2.2.1

Internal Electrical Configuration of the S5-90U

The S5-90U's onboard I/Os allow a floating configuration.
The ten onboard inputs have a common ground connection. The ground connection is attached to
the negative pole of the PLC's 24 V DC voltage source. Optocouplers separate all inputs from the
control circuit's ground.
The six onboard outputs are relay outputs. The connections for the relay contacts are separate and
do not have a mutual connection.
Power supply for
the S5-90U
115/230 V
+U int
Data
GND
Figure 2-5. A Simplified Display of the Floating Onboard I/Os
EWA 4NEB 812 6115-02b
Voltage source
for sensor
+ -
+ 24 V
AC
24 V
DC
M 24 V
Digital outputs
Technical Description
Digital inputs
Total of 10 digital inputs
M 24 V
2-5