Filter
Top Products
Reference Manual
300530EN, Rev BA
September 2012
3-21
Rosemount 2410
Section 3. Installation
3.4.9 Cabling for the
TRL2/RS485 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 mm
2
(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:
Table 3-5. Minimum cable area
for the TRL2 bus
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.
Figure 3-13. Individually
shielded pair cables minimizes
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
RS485 Bus
The RS485 bus should meet the following requirements:
• twisted and shielded pair wiring
• characteristic impedance of 120
• maximum cable length 1200 m / 4000 ft.
Maximum distance Minimum cross-sectional area
3 km 0.50 mm
2
(AWG 20)
4 km 0.75 mm
2
(AWG 18)
Type Manufacturing standard Core size
Signal BS 5308 part 1, type 1 1 mm
2
Signal (armoured) BS 5308 part 2, type 1 1 mm
2