Rosemount 2240S, Справочное руководство

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Reference Manual
300550en, Rev AA
December 2010
4-9
Rosemount 2240S
Section 4. 2240S Installation
4.4.6 The Raptor
Tankbus
The Raptor system is easy to install and wire. Devices can be “daisy-chained”
thus reducing the number of external junction boxes.
In a Raptor system devices communicate with a Rosemount 2410 Tank Hub
via the intrinsically safe Tankbus. The Tankbus complies with the FISCO
(1)
F
OUNDATION
fieldbus standard. The Rosemount 2410 acts as power supply to
the field devices on the Tankbus. A FISCO system enables more field devices
to be connected to the segment compared to conventional IS systems based
on the entity concept.
Termination
A terminator is needed at each end of a F
OUNDATION
Fieldbus network.
Generally, one terminator is placed in the fieldbus power supply, and the other
one in the last device in the fieldbus network.
NOTE!
Ensure there are two terminators on the Tankbus, see Figure 4-3.
In a Raptor system the Rosemount 2410 Tank Hub acts as power supply.
Since the 2410 normally is the first device in the fieldbus segment, the built-in
termination is enabled at factory
Other Raptor devices such as the standard version of the Rosemount 5900S
Radar Level Gauge, the Rosemount 2230 Graphical Field Display, and the
Rosemount 2240S Multi-input Temperature Transmitter also have built-in
terminators which can easily be enabled by inserting a jumper in the terminal
block when necessary.
If the 2240S is not the last device in the fieldbus network, disconnect the
termination jumper. See Figure 4-4 on page 4-11.
Segment design
When designing a FISCO fieldbus segment a few requirements need to be
considered. Cabling has to comply with FISCO requirements as described in
“Cable Selection” on page 4-8.
You will also have to ensure that the total operating current of the connected
field devices is within the output capability of the Rosemount 2410 Tank Hub.
The 2410 is able to deliver 250 mA. Consequently, the number of field devices
has to be considered so that the total current consumption is less than
250 mA. See section “Power Budget” in the Rosemount 2410 Reference
Manual (Document No. 300530EN) for more information
Another requirement is to ensure that all field devices have at least 9 V input
voltage at their terminals. Therefore you will have to take into account the
voltage drop in the fieldbus cables.
Distances are normally quite short between the Rosemount 2410 Tank Hub
and field devices on the tank. In many cases you can use existing cables as
long as the FISCO requirements are fulfilled (see “Cable Selection” on
page 4-8).
See chapter “The Raptor Tankbus” in the Rosemount 2410 Reference Manual
(Document no. 305030EN) for more information on segment design of a
Raptor system.
(1) FISCO=Fieldbus Intrinsically Safe Concept