DS2/DS4 Hardware Manual
Page 38
5.8
AIM104 – HBI
The AIM104-HBI board provides up to 2 channels of HART protocol and 2 analog outputs. Power
consumption of the AIM104-HBI is 1 Watt, excluding loop power. The I/O specification is given in
following sections.
HART (Highway Addressable Remote Transducer) protocol is a common "Smart" device protocol used
widely in instrumentation systems. It allows traditional analog devices to offer enhanced functionality by
adding a digital communication protocol without interrupting the existing 4-20 milliamp current signal.
Enhanced functionality often includes measurement of more than one process variable, configuration of
device parameters and tag names, and remote calibration.
Each HART channel allows one device in point-to-point mode (standard 4-20 mA), or up to 15 devices in
multidrop mode. When point-to-point mode is used for field devices, the 4-20 mA signal may be connected to
a standard analog input of a control system, with the AIM104-HBI board connected in parallel for
communication. Devices in multidrop mode generally fix the current signal at a constant four millamps, and
the AIM104-HBI is used in place of an analog input. In either case, the AIM104-HBI board communicates to
the device using the digital HART protocol, and does not measure the 4-20 mA current signal.
The analog outputs are provided for applications requiring an additional control signal, such as valve
positioners.
See the
Protocol Manual
for more information on the physical and data link layers of the HART Protocol.
5.8.1
HART Input Specifications
Number of HART Inputs
2 channels, capable of up to 1 point-to-point device
or 15 multidrop devices per channel
Scan Time for HART Process Variables
Timing depends on ACE configuration, minimum
1/3 second per HART device (assuming no
communication retries)
Isolation
2000 V transformer isolation
5.8.2
Analog Output Specifications
Number of Analog Outputs
2
Voltage/Current Range Options
0 to 5 Vdc (0 to 20 mA with 250
Ω
resistor)
1 to 5 Vdc (4 to 20 mA with 250
Ω
resistor)
Output type depends on ISaGRAF configuration
Resolution
12 bits
Isolation
1000 V opto-isolation
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