Siemens SIMATIC S7-1500 Manual page 19

Pin assignment for the infeed element
The infeed element is inserted into the front connector and serves to supply power to the
technology module. You must connect the supply voltage to terminal 41 (L+) and terminal 44
(M) for this.
Figure 3-1
L+
M
Behavior of the digital outputs following a wire break at the ground connection of the outputs
Due to the characteristics of the output driver used in the module, a wire break causes
approximately 10 mA supply current to drain from the digital outputs via a parasitic diode.
This behavior may lead to a high signal state even at outputs that are not set. Depending on
the nature of the load, 10 mA may be enough to activate a load with high signal state.
Duplicate wiring of ground
To prevent unintended switching of the outputs in the event of a ground connection wire
break, follow these steps:
1. Route the first ground connection from terminal 44 to the ground connection of the central
power supply of the system.
2. Route the second ground connection from terminal 43 to the ground connection of the
central power supply of the system.
If one of the two ground connection cables is interrupted, the outputs are maintained at the
required potential by the remaining ground connection.
Wire break at ground connection
Always connect
system.
Technology Module TM PTO 4 (6ES7553-1AA00-0AB0)
Manual, 12/2016, A5E38896703-AA
Infeed element wiring
24 V DC supply voltage
Ground for supply voltage
WARNING
two
cables to the ground connection of the central power supply of the
Connecting
3.1 Pin assignment
19