Reference Manual

00809-0100-4697, Rev EA October 2011

Rosemount 848T

Block Execution

The ISEL function block reads the values and status of up to eight inputs. To specify which of the six available methods (algorithms) is used to select the output, configure the selector type parameter (SELECT_TYPE) as follows:

Max selects the maximum value of the inputs.

Min selects the minimum value of the inputs.

Avg calculates the average value of the inputs.

Mid calculates the update for eight sensors.

1st Good selects the first available good input.

If the DISABLE_N is active, the associated input is not used in the selection algorithm.

If an input is not connected, it is also not used in the algorithm.

If the OP_SELECT is set to a value between 1 and 8, the selection type logic is overridden and the output value and status is set to the value and status of the input selected by OP_SELECT.

SELECTED will have the number of selected input unless the SELECT_TYPE is mid, in which case it will take the average of the two middle values. Then SELECTED will be set to “0” if there is an even number of inputs.

Status Handling

In Auto mode, OUT reflects the value and status quality of the selected input. If the number of inputs with Good status is less than MIN_GOOD, the output status will be Bad.

In Man mode, the OUT status high and low limits are set to indicate that the value is a constant and the OUT status is always Good.

In the STATUS_OPTS parameter, select from the following options to control the status handling:

Use Uncertain as Good

Sets the OUT status quality to Good when the selected input status is Uncertain.

Uncertain if in Manual mode

The status of the Output is set to Uncertain when the mode is set to manual.

NOTE

The instrument must be to OOS to set the status option.

Application Information

Use the ISEL function block to:

Select the maximum temperature input from eight inputs and send it to another function block (see Figure D-6)

Calculate the average temperature of the eight inputs (see Figure D-7)

Use only six of the eight inputs to calculate the average temperature.

D-19

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Emerson 848T manual Block Execution, Use Uncertain as Good

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.