Emerson Process Management Rosemount 2410 manual Cabling for the TRL2/RS485 Bus, TRL2 Bus

Reference Manual

300530EN, Rev BA September 2012

Rosemount 2410

3.4.9Cabling for the TRL2/RS485 Bus

Table 3-5. Minimum cable area for the TRL2 bus

In a Raptor system a Rosemount 2410 Tank Hub communicates with a 2160 Field Communication Unit using the TRL2/RS485 Modbus protocol, see Section 2: Overview.

TRL2 Bus

The TRL2 bus requires twisted and shielded pair wiring with a minimum

cross-sectional area of 0.50 mm2 (AWG 20 or similar). The maximum length of the TRL2 bus is approximately 4 km /13000 ft. The TRL2 field bus can normally use existing cables in the tank area.

Cable cross-sectional area for the TRL2 wiring should follow the recommendations in Table 3-5:

Maximum distance	Minimum cross-sectional area
3 km	0.50 mm2 (AWG 20)
4 km	0.75 mm2 (AWG 18)

Figure 3-13. Individually shielded pair cables minimizes crosstalk

NOTE!

Wherever two or more TRL2 buses run alongside each other, sharing the same cable or conduit tube, use twisted and shielded wire and ensure that each pair of bus wires is individually shielded in order to avoid crosstalk.

Table 3-6 shows typical cable types that can be used for connecting the TRL2 bus. Other cables of similar type may also be used.

Table 3-6. Recommended cable standards for the TRL2 bus

Type	Manufacturing standard	Core size
Signal	BS 5308 part 1, type 1	1 mm2
Signal (armoured)	BS 5308 part 2, type 1	1 mm2

RS485 Bus

The RS485 bus should meet the following requirements:

•twisted and shielded pair wiring

•characteristic impedance of 120 Ω

•maximum cable length 1200 m / 4000 ft.

Section 3. Installation 3-21