Siemens SITRANS F M TRANSMAG 2, Руководство по эксплуатации, Страница: 94 / 114

Profibus Communication
B.2 Wiring devices with Profibus PA
SITRANS F M TRANSMAG 2
92
Operating Instructions, 11/2009, A5E00102775-07
B.2 Wiring devices with Profibus PA
WARNING
Lid over terminals for power supply may not be removed! Use only certified measuring
instruments!
The Profibus PA variant of the SITRANS F M Transmag 2 differs from the HART variant with
the 4-20 mA output in the bus interface and the omission of the digital output 2. The basic
functions of the device including the operation and display remain basically the same.
The Transmag 2 terminals 7 and 8 are reserved for the Profibus PA connection.
● 7: PA wire 1. This device is polarity independent
● 8: PA wire 2. This device is polarity independent
The PA interface is polarity independent, so the wires can be connected arbitrarily.
PA supports LINE, DROP, STAR topology and a combination of the three.
A
Figure B-1 PA wiring
B
Figure B-2 PA wiring with T-connector
Shielding
● Only use shielded cables for the PROFIBUS connection. Any connection polarity is
possible.
● The shield must be laid to cover all assigned terminal boxes, distributors up to the coupler
or link.
● The shield must be connected and fixed with the shield clamp.
● To achieve the best EMC performance, the unshielded wires should be as short as
possible, 3-4 cm.