Rockwell Automation RECOMM-PBUS PROFIBUS Communications Module - Manual (Page 20)

3-4 PROFIBUS Communications Module
Step 5. Connect the PROFIBUS cable to the module, and secure
it with the two screws on the connector. (See figure 3.5.)
Note: The screws on some connectors tie the PROFIBUS
cable ground/shield to the metal of the socket. In some
cases, PROFIBUS will not operate correctly without this
connector.
3.4 Terminating the Network
The first and last node on the PROFIBUS network needs to be
terminated by using a PROFIBUS connector with terminating
resistors.
Some connector manufacturers offer standard terminating
connectors, such as the yellow ERNI PROFIBUS termination
vertical connector (Part # 103659). Standard PROFIBUS node
connectors, such as the Phoenix Subcon Plus M1 (Part #2761826),
can be configured as a terminating connector by adding resistors
(see figure 3.4.)
6 +5V BUS Isolated +5V from
bus
7 Not connected
8 A-LINE Negative RxD/TxD
according to RS485
specification
9 Not connected
Table 3.1 – RECOMM-PBUS DB-9 Pin Layout (Continued)
Terminal Signal Function
Figure 3.4 – Phoenix Subcon Plus M1 Connection for Terminating Resistors
6
3
8
5
390
220
390
Ω
Ω
Ω
B
A