Emerson Star Topology, Alternative Multidrop Connection of 5300/5400 Transmitters

Rosemount 5300/5400 Series

Manual Supplement

00809-0500-4530, Rev AA October 2010

Alternatively, the Rosemount 5300/5400 Series Transmitters can be installed as shown in Figure 1-5. If this wiring layout is used, there is an increased risk for communication disturbances due to differences in potential between grounding points. By using the same grounding point for Modbus Master and Power Supply, this risk is reduced.

Figure 1-5. Alternative Multidrop

Connection of 5300/5400

Transmitters

120Ω RS-485 Bus

HART to Modbus Converter

MB

	MODBUS MA	-
	(RS-485)
-	POWER	+
	HART Ambients > 60 ºC
+	Use wiring rated
	for min 90 ºC

HART to Modbus Converter

MB

	MODBUS MA	-
	(RS-485)
-	POWER		+
	HART Ambients > 60 ºC
+	Use wiring rated
	for min 90 ºC

120Ω

BModbus

A Master

Z

Internal	Internal
Ground Screw	Ground Screw
External	External
Ground Screw	Ground Screw

Star Topology

Power Supply

For a Star Topology Connection of the 5300/5400 transmitters, the transmitter with the longest cable run needs to be fitted with a 120-Ωtermination resistor.

Figure 1-6. Star Topology

Connection of 5300/5400

Transmitters

verter

MB

MODBUS MA

(RS-485) -

For Star Topology connection, connect the 120Ω termination resistor to the transmitter with the longest cable run.

1-8