Connecting Profibus Dp; Disconnecting Stations From The Profibus - Siemens SINUMERIK ONE NCU 1750 Equipment Manual

8.9.5

Connecting PROFIBUS DP

Introduction
PROFIBUS cables are connected to the X126 interface via a bus connector.
Wiring the bus connector
1. Proceed as follows to connect the bus connector:
2. Plug the bus connector into the corresponding interface on the NCU.
3. Screw the bus connector into place.
As the NCU is located at the start or end of a segment, you must switch on the terminating
resistor ("ON" switch setting).
Figure 8-7
Note
Make sure that the stations on which the terminating resistor is located are always supplied
with voltage during ramp-up and operation.
8.9.6

Disconnecting stations from the PROFIBUS

Removing the bus connector
You can remove the bus connector with a looped-through bus cable from the PROFIBUS DP
interface at any time without interrupting data traffic on the bus.
NOTICE
Data exchange on the bus can be interrupted!
A bus segment must always be terminated with the terminating resistor at both ends. This is
not the case, for example, if the last node with a bus connector is de-energized. Because the bus
connector takes its voltage from the node, this terminating resistor is ineffective.
Make sure that the nodes at which the terminating resistor is connected are always energized.
NCU 1750
Equipment Manual, 01/2022, A5E45627807B AE
Terminating resistor switched on and off
Connecting
8.9 PROFIBUS DP
79