Handheld communicator Model DHH805-A |
OI/DHH805-EN Rev. D 17
7 HART
®
Communication
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7 HART
®
communications
7.1 Overview
DHH805-A provides device specific HART
®
communication functions that allow the user to poll, configure, and maintain supported
HART
®
field devices. The handheld communicator uses all Device Description commands to facilitate communication with a
HART
®
field device.
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
®
device through Universal and Common Practice Commands using the standard
Generic DD (Device Description). However, it must have the DD for a specific HART
®
device installed before it can execute Device
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.
The list is found under Product Catalogue > All products. When HART
®
device support for new devices becomes available, the
DHH805-A can can easily be field updated using the dedicated PC-Tool.
7.2 HART
®
Commands
Three HART
®
command types are used by the DHH805-A to communicate with HART
®
field devices. First, Universal Commands
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
®
Device. Second, Common Practice Commands are used for calibration and maintenance
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.
7.3 HART
®
Connections
HART
®
connections are made using two standard banana jacks (3/4” center) located at the top end of the handheld terminal (see
figure 1). Polarity is not a concern for HART
®
connections, therefore, both jack collars are blue. ABB supplies a HART
®
lead kit
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
®
communications. Refer
to the following diagram for connection details.
Figure 14: DHH805-A wiring
1 Internal ground termination | 2 External ground termination | 3 DHH805-A | 4 Line load | 5 Power supply unit
Hazardous classified location
Unclassified location
3
2
1
4
Содержание DHH805-A
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