Siemens SIMATIC NET 12M Operating Instructions Manual page 9

Terminal block
Short name
PE
A1
B1
A2
B2
PE
Terminal block
The following is recommended for PROFIBUS:
● Terminal A - green wire
● Terminal B - red wire
Termination
Activate the termination on the first and last node of the bus segment.
If termination is activated (termination on), the connection between the incoming (A1, B1)
and outgoing (A2, B2) segment is interrupted. If the wrong bus terminating resistors are
activated, it is no longer possible to access stations downstream from the bus terminal.
When a segment is put into operation, there must therefore be no bus terminating resistors
activated that are not located at the start or end of the network.
D-sub male connector
The D-sub male connector is plugged into the D-sub female connector of the DTE and
secured by screws. The 12M bus terminal requires a current of 90 mA with a voltage of 5 V
supplied by the DTE between pins 5 (M5) and 6 (P5) of the D-sub male connector.
Pin no.
1
2
3
4
5
6
7
8
9
Casing
D-sub male connector pinout
The impedance of the PROFIBUS interface when receiving must be ≥ 10 kilohms (according
to the EIA standard RS-485). The spur line must not be terminated.
12M bus terminal
Siemens Distributor
Operating Instructions, 07/2013, C79000-G8976-C333-01
Meaning
Protective earth connected to the cable shield and DIN rail
Signal line A of the incoming segment side
Signal line B of the incoming segment side
Signal line of the outgoing segment side
Signal line of the outgoing segment side
Protective earth connected to the cable shield and DIN rail
Short name Meaning
PE Protective earth, connected to the cable shield
nc
B (RxD/TxD-P) Signal line B
nc
M5 (DGND) Chassis connection of the 5 volt supply
P5 (VP) + 5 volt connection, 90 mA required
nc
A (RxD/TxD-N) Signal line A
nc
PE Protective earth, connected to the cable shield
Introduction
1.2 Description of the product
9