Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual page 106

Wiring
6.5 Wiring front connectors
Requirements
The modules (SM, FM, CP 342-2) are mounted on the rail.
Preparing the front connectors and cables
Warning
There is a risk of contact to live wires if the power supply module, or any additional load
power supply units, are connected to the mains.
You should therefore isolate the S7-300 from power before you start wiring it. Close all front
panels of the modules when you completed the wiring. This is conditional before you
reconnect the S7-300 to power.
1. Switch off the power supply.
2. Open the front panel.
3. Place the front connector into wiring position.
4. Strip the conductors to a length of 6 mm.
5. Crimp the wire end ferrules, for example, to terminate two conductors at one terminal.
P S
The figure illustrates the following
(1)
(2)
(3)
6-8
Push the front connector into the signal module until it latches. In this position, the front
connector still protrudes from the module.
Advantage of this wiring position: Comfortable wiring.
The front connector pins do not contact the module in this wiring position.
2 2
C P U
3 2
1 2
The switched off power supply module (PS)
The opened module
The front connector in wiring position
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05