Emerson Process Management Rosemount 2410 manual Tankbus, Termination, Fieldbus Segment Design

Reference Manual

Rosemount 2410

300530EN, Rev BA September 2012

3.4.7Tankbus

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 the field devices communicate with a Rosemount 2410 Tank Hub via the intrinsically safe Tankbus. The Tankbus complies with the FISCO(1) FOUNDATION fieldbus standard with the Rosemount 2410 acting as a power supply to the field devices on the Tankbus.

The Rosemount 2410 is designed for use in hazardous area Zone 1 (Class 1, Division 1) and communicates with field devices via the intrinsically safe Tankbus.

Termination

A terminator is needed at each end of the trunk in a FOUNDATION fieldbus network. A trunk is defined as the longest cable path between two devices on the fieldbus network. In the Raptor system, a trunk is typically located between the 2410 Tank Hub and a splitter or the last device in a daisy-chain configuration. Generally, one terminator is placed in the fieldbus power supply, and the other one in the last device in the fieldbus network as illustrated in Figure 3-7.

NOTE!

Ensure that there are two terminators on the fieldbus.

In a Raptor system the Rosemount 2410 Tank Hub acts as a 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 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.

When adding new devices at the end of an existing FOUNDATION fieldbus network, the termination is moved to the farthest field device in order to fulfill the requirement on locating the terminator at the end of the trunk. However, in case a field device is added to the network with a short cable, this rule may be slightly bent by leaving the terminator in its original position.

Fieldbus Segment Design

When designing a FISCO fieldbus segment you will have to make sure that cabling complies with FISCO requirements as described in “Cable Selection for the Tankbus” on page 3-6.

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 total number of field devices has to be considered so that the total current consumption is less than 250 mA, see “Power Budget” on page 3-7.

(1)FISCO=Fieldbus Intrinsically Safe Concept

3-8 Section 3. Installation