Hart ® Communications; Overview; Hart ® Commands; Hart ® Connections - ABB DHH805-A Operating Instruction

7 HART communications
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7.1 Overview

DHH805-A provides device specific HART
HART field devices. The handheld communicator uses all Device Description commands to facilitate communication with a
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HART field device.
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You can use the DHH805-A to commission devices, for operational re-configuration needs, delete or maintain devices through
analog and sensor trim adjustments, and many other features.
The DHH805-A will communicate with any HART
Generic DD (Device Description). However, it must have the DD for a specific HART
Specific Commands. You can consult the large and growing list of available DD at www.hartcomm.org for an up-to-date list of
HART devices for device specific support.
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The list is found under Product Catalogue > All products. When HART
DHH805-A can can easily be field updated using the dedicated PC-Tool.
7.2 HART Commands
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Three HART command types are used by the DHH805-A to communicate with HART
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are primarily used to identify a field device by its model number and tag number and to read process data from the device. This
communication is referred to as "polling".
The DHH805-A can poll any HART
functions that are common to many devices. An example of this would be trims or adjustments for the devices' analog outputs.
Third, Device Specific Commands are used to handle functions that are unique to a particular device or manufacturer. Examples of
these commands include sensor zero, sensor trim, calibration curve characterization, density inputs required for calculations made
by the HART device, or other configuration functions unique to the specific device.
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7.3 HART Connections
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HART connections are made using two standard banana jacks (3/4" center) located at the top end of the handheld terminal (see
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figure 1). Polarity is not a concern for HART
complete with mini-grabber connections.
For low load loops (less than 250 Ω), a 250 Ω resistor may be needed in the loop to insure reliable HART
to the following diagram for connection details.
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1 Internal ground termination | 2 External ground termination | 3 DHH805-A | 4 Line load | 5 Power supply unit
Figure 14: DHH805-A wiring
communication functions that allow the user to poll, configure, and maintain supported
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device through Universal and Common Practice Commands using the standard
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Device. Second, Common Practice Commands are used for calibration and maintenance
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connections, therefore, both jack collars are blue. ABB supplies a HART
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5
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Unclassified location
device installed before it can execute Device
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device support for new devices becomes available, the
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Handheld communicator Model DHH805-A | OI/DHH805-EN Rev. D 17
7 HART Communication
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field devices. First, Universal Commands
communications. Refer
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Hazardous classified location
lead kit
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