Siemens SIMATIC S7-1500 Manual page 16

Wiring
4.1 Terminal assignment
24 V DC supply voltage
The following table shows the signal names and the descriptions of the terminal assignment
for a 24 V DC supply voltage.
Table 4- 1
1L+ and 2L+ as well as 1M and 2M are bridged internally
1
Maximum 10 A permitted
2
The length of the connectable 24 V DC supply cable is limited to max. 30 m for EMC reasons.
USB 3.1 interface
The USB 3.1 interface is designed with a type A connection socket. The plug connector does
not have a strain relief. You should therefore use a cable tie for strain relief of the USB cable.
Use a 2.5 mm wide cable tie for strain relief.
The figure below shows the TM NPU with installed cable tie.
Figure 4-2
Only connect sensors and cables to the USB interface in which the shield and ground signal
are galvanically isolated.
For sensors and cables whose shield and ground (PIN 4) are connected to each other, an
impermissible current flows over the cable shield in the event of a ground fault of the
24 V DC supply. The impermissible current flows over the shield spring of the module and the
grounded mounting rail.
14
Terminal assignment 24 V DC supply voltage
View Signal name
1L+
2L+
1M
2M
Strain relief for USB cable
1
24 V DC
24 V DC (for looping through)
Ground
Ground (for looping through)
Equipment Manual, 09/2020, A5E46384784-AA
Description
2
2
Technology Module TM NPU