AI Block Troubleshooting, Application Information

Rosemount 848T

Reference Manual

00809-0100-4697, Rev EA October 2011

Application Information

The configuration of the AI function block and its associated output channels depends on the specific application. A typical configuration for the AI block involves the following parameters:

CHANNEL

The device supports more than one measurement, so verify that the selected channel contains the appropriate measurement or derived value. Refer to Table 3-5 on page 3-11for a listing of available channels on the 848T.

L_TYPE

Select Direct when the measurement is in the desired engineering units for the block output. Select Indirect when converting the measured variable into another, for example, pressure into level or flow into energy.

SCALING

XD_SCALE provides the range and units of the measurement and

OUT_SCALE provides the range and engineering units of the output.

OUT_SCALE is only used when in indirect or indirect square root.

AI Block

Troubleshooting

Symptom	Possible Causes	Corrective Action
Mode will not leave OOS	Target mode not set.	Set target mode to something other than OOS.
	Configuration error	BLOCK_ERR will show the configuration error bit set. The following are parameters that
		must be set before the block is allowed out of OOS:
		• CHANNEL must be set to a valid value and cannot be left at initial value of 0.
		• XD_SCALE.UNITS_INDEX must match the units in the transducer block
		channel value. Setting the units in the AI block automatically sets them in the
		XD_BLOCK.
		• L_TYPE must be set to Direct, Indirect, or Indirect Square Root and cannot be left at
		initial value of 0.
	Resource block	The actual mode of the Resource block is OOS. See Resource Block Diagnostics for
		corrective action.
	Schedule	Block is not scheduled and therefore cannot execute to go to Target Mode. Typically,
		BLOCK_ERR will show “Power-Up” for all blocks that are not scheduled. Schedule the
		block to execute.
Process and/or block	Features	FEATURES_SEL does not have Alerts enabled. Enable the Alerts bit.
alarms will not work.	Notification	LIM_NOTIFY is not high enough. Set equal to MAX_NOTIFY. Alarm not linked to host.
	Status Options	STATUS_OPTS has Propagate Fault Forward bit set. This should be cleared to cause an
		alarm to occur.
Value of output does not	Linearization Type	L_TYPE must be set to Direct, Indirect, or Indirect Square Root and cannot be left at
make sense		initial value of 0.
	Scaling	Scaling parameters are set incorrectly:
		• XD_SCALE.EU0 and EU100 should match that of the transducer block
		channel value.
		• OUT_SCALE.EU0 and EU100 are not set properly.
		• Both STB on each asic used must by in auto.
Cannot set HI_LIMIT,	Scaling	Limit values are outside the OUT_SCALE.EU0 and OUT_SCALE.EU100 values.
HI_HI_LIMIT, LO_LIMIT,		Change OUT_SCALE or set values within range.
or LO_LO_LIMIT Values

D-8

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.

Emerson 848T manual AI Block Troubleshooting, Application Information, Xdblock, HIHILIMIT, Lolimit

Models: 848T