Reference Manual

00809-0100-4697, Rev EA October 2011

Rosemount 848T

Appendix C FOUNDATIONfieldbus Technology

OVERVIEW

FUNCTION BLOCKS

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page C-1 Function Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page C-1 Device Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page C-3 Block Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page C-3 Network Communication . . . . . . . . . . . . . . . . . . . . . . . . . . page C-4

FOUNDATION fieldbus is an all-digital, serial, two-way, multidrop communication protocol that interconnects devices such as transmitters, sensors, actuators, and valve controllers. Fieldbus is a Local Area Network (LAN) for instruments that are used in both process and manufacturing automation, having the built-in capability to distribute the control applications across the network. The fieldbus environment is the base level group of digital networks and the hierarchy of plant networks.

The FOUNDATION fieldbus retains the desirable features of the 4–20 mA analog system, including standardized physical interface to the wire, bus-powered devices on a single pair of wires, and intrinsic safety options. It also enables the following capabilities:

Increased capabilities due to full digital communication.

Reduced wiring and wire terminations due to multiple devices on one pair of wires.

Increased supplier selection due to interoperability

Reduced loading on control room equipment due to the distribution of some control and input/output functions to field devices.

FOUNDATION fieldbus devices work together to provide I/O and control for automated processes and operations. The Fieldbus FOUNDATION provides a framework for describing these systems as a collection of physical devices interconnected by a fieldbus network. One of the ways that the physical devices are used is to perform their portion of the total system operation by implementing one or more function blocks.

Function blocks perform process control functions, such as analog input (AI) and analog output (AO) functions as well as proportional-integral-derivative (PID) functions. The standard function blocks provide a common structure for defining function block inputs, outputs, control parameters, events, alarms, and modes, and combining them into a process that can be implemented within a single device or over the fieldbus network. This simplifies the identification of characteristics that are common to function blocks.

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Emerson 848T manual Appendix C Foundation fieldbus Technology, Overview Function Blocks

848T specifications

The Emerson 848T is a state-of-the-art temperature transmitter designed for accurate and reliable temperature measurement in various industrial applications. This device has gained recognition for its advanced features and robust performance, making it a popular choice among engineers and technicians in the field.

One of the key highlights of the Emerson 848T is its unique dual-channel capability, which allows it to seamlessly monitor two temperature sources simultaneously. This functionality is particularly beneficial in processes where multiple temperature points need to be assessed, optimizing efficiency and reducing the need for additional equipment. It supports various sensor types, including thermocouples, RTDs, and resistance temperature detectors, making it versatile for different applications.

The 848T is equipped with sophisticated digital processing technology, which enhances its accuracy and stability. It features a 24-bit analog-to-digital converter, ensuring precise measurement and minimizing drift over time. Moreover, the device boasts a wide operating temperature range, accommodating ambient conditions from -40°C to 85°C. This durability makes it suitable for harsh environments commonly encountered in industries such as oil and gas, pharmaceuticals, and power generation.

Another significant characteristic of the Emerson 848T is its configurable output options. Users can choose from a range of output signals, including 4-20 mA, which provides a standard interface for integration into existing control systems. Additionally, it offers a HART communication protocol, allowing for easy configuration, calibration, and diagnostics through a digital interface. This feature enhances the transmitter's usability, enabling operators to perform adjustments without direct access to the device.

The device is designed with user-friendliness in mind. Its intuitive setup procedure and robust graphical user interface simplify the commissioning process, ensuring that even those new to the technology can easily navigate the system. An integrated LCD display provides real-time readings and status information, facilitating monitoring at a glance.

In summary, the Emerson 848T temperature transmitter combines reliable performance, user-friendly design, and advanced digital technologies. Its dual-channel capability, wide sensor compatibility, and adjustable output options make it an essential tool for achieving precise temperature measurements in various industrial settings. With these compelling features, the Emerson 848T stands out as a leading choice for professionals seeking accuracy and efficiency in their temperature monitoring applications.