Siemens SIMATIC NET PROFIBUS manual Disconnect Function, Disconnecting a Station

Passive Components for RS-485 Networks

Disconnect Function

The disconnect function means that the remaining LAN cable is disconnected from the bus when the terminating resistor is activated. If the terminating resistor is accidentally activated in the middle of the LAN cable, the error can be recognized and localized immediately due to the nodes that are no longer accessible.

Disconnecting a Station

The bus connector allows you to disconnect a node from the bus without interrupting the data traffic on the bus.

Removing the bus connector when the terminating resistor is activated at the end of the cable causes disruptions on the bus and is not permitted.

Bus Connector with PG Socket

We recommend that you include at least one bus connector with a PG socket in each bus segment. This makes it easier to commission using a programming device or PC.

In the bus connectors with a PG socket, all the contacts are connected 1:1 with the connector pins; in other words, the pinout is the same as the pinout of the attached device.

Pinout of the Sub-D Male Connector

Table 4-5 shows the pinout of the 9-pin sub-D male connector.

Table 4-5 Pinout of the 9-pin Sub-D Male Connector

Pin	Signal	Meaning
no.	name
1	-	-
2	-	-
3	RxD/TxD-P	Data line B
4	–	–
5	M5V2	Data reference potential (from node)
6	P5V2	Power supply plus (from node)
7	-	-
8	RxD/TxD-N	Data line A
9	-	-

4-28	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000