Siemens SIMATIC S7-300 CPU Manual page 8

2 Solution
2.1 Overview of the general solution
Components included
The following table represents a list of the used hardware components.
Table 2-1
No.
1 SITOP PSE200U with
single-channel signaling
2 Load circuits
3 Status output (S)
4 Digital input module /
Digital output module
(DI/DO)
5 SIMATIC S7-300/400 CPU
6 SIMATIC Panel
7 Power Supply (PS)
8 Remote reset input (RST)
Monitoring of 24 V load circuits
Entry-ID: 61450284, V1.1,
Component
05/2014
Description
The PSE200U module is connected to a 24 V DC
power supply. The output voltage (24 V DC)
generated by the power supply is divided between
four load circuits.
The load circuits are connected to outputs OUT 1
to OUT 4 of the PSE200U module, e.g.:
motor at output OUT 1
lighting at output OUT 2
The state output (S) of the PSE200U module
supplies a signal that serially codes the states of all
four outputs OUT 1 to OUT 4.
The signal of status output (S) of the S7-CPU is
read via the digital input module.
Via a digital output, the remote reset input (RST) of
the PSE200U module is controlled by the S7-CPU.
In the user program of the S7-CPU, the signal of
the status output (S) is evaluated to monitor the
states of the load circuits connected at outputs
OUT 1 to OUT 4 of the PSE200U module.
The S7-CPU detects:
output OUT 1 of the PSE200U module is
switched off, e.g. due to an overload at the
connected motor
output OUT 2 of the PSE200U module is
switched off, e.g. due to a short circuit of the
connected lighting
The SIMATIC Panel indicates:
states of the load circuits
messages on state changes at the load
circuits
24 V DC power supply with an output current of up
to 40 A.
If outputs OUT 1 to OUT 4 of the PSE200U module
were automatically switched off due to a failure,
e.g. overload or short-circuit, they can be switched
back on after a wait time of 20s via the remote
reset input (RST).
In the application, the remote reset input (RST) is
controlled via the SIMATIC Panel (8a). However, it
can also be controlled directly by pressing a button
(8b).
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