Siemens SIMATIC NET PROFIBUS Properties, How the DP/PA Link Works, PA master, DP/PA coupler Max

Topologies of SIMATIC NET PROFIBUS Networks

Properties

The DP/PA link has the following characteristics:

SDiagnostics with LEDs and the user program

SDP slave and PA master

SCan be operated at all transmission rates (9.6 Kbps to 12 Mbps)

SOnly DP/PA couplers can be operated with an IM 157

How the DP/PA Link Works

Figure 2-17 shows how the DP/PA link with the IM 157 and the DP/PA couplers functions.

SThe DP/PA link maps the underlying PROFIBUS-PA system on a DP slave.

SWith the DP/PA link, PROFIBUS-DP is completely isolated from

PROFIBUS-PA.

SThe PA master and PA slaves form a separate, underlying bus system.

SThe number of DP/PA couplers simply reflects the amount of current required. All DP/PA couplers along with the attached PA field devices form one common PROFIBUS-PA bus system.

DP/PA Link

	DP
IM 157	DP slave		PA master
		S7 backplane bus
	DP/PA coupler
	(max. 5)	PA	PA
		PA	PA

Figure 2-17 The DP/PA Link with DP/PA Couplers

2-26	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000