Rosemount 848T

Reference Manual

00809-0100-4697, Rev EA October 2011

Function Block

Scheduling

Figure C-6. Example Link

Schedule Showing Scheduled

and Unscheduled

Communication

Figure C-6shows an example of a link schedule. A single iteration of the link-wide schedule is called the macrocycle. When the system is configured and the function blocks are linked, a master link-wide schedule is created for the LAS. Each device maintains its portion of the link-wide schedule, known as the Function Block Schedule. The Function Block Schedule indicates when the function blocks for the device are to be executed. The scheduled execution time for each function block is represented as an offset from the beginning of the macrocycle start time.

 

 

 

 

Macrocycle Start Time

 

Sequence

 

 

 

 

 

 

 

 

 

 

Repeats

 

 

 

 

 

Offset from macrocycle

 

 

 

 

 

 

 

 

 

 

 

 

start time = 0 for AI

 

 

 

 

 

 

Device 1

 

 

 

Execution

 

 

AI

 

 

 

 

 

AI

 

 

 

 

 

 

 

 

 

 

 

 

Scheduled

 

 

 

 

 

 

Offset from macrocycle

 

start

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

time = 20 for AI Communication

 

 

 

Communication

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Unscheduled

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Communication

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Offset from macrocycle start

 

Device 2

 

 

 

 

 

 

 

 

time = 30 for PID Execution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PID

 

AO

 

PID

AO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Offset from macrocy

cle start

 

 

 

 

 

 

 

 

 

 

 

time = 50 for AO Execution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Macrocycle

To support synchronization of schedules, periodically Link Scheduling (LS) time is distributed. The beginning of the macrocycle represents a common starting time for all Function Block schedules on a link and for the LAS link-wide schedule. This permits function block executions and their corresponding data transfers to be synchronized in time.

C-8

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Emerson 848T manual Function Block Scheduling

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.