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ROC800-Series Instruction Manual
Revised Jul-14
Input/Output Modules
4-31
4.14 Highway Addressable Remote Transducer (HART
®
) Module
Note
:
The HART-2 module (labeled
HART-2
with black faceplate)
replaces the HART module (with gray faceplate).
The HART-2 module allows a ROC800 to communicate with HART
devices using the HART protocol. The HART-2 module receives
signals from and transmit signals to HART devices. LEDs provide a
visual indication of the status of each HART channel. Refer to
Figure 4-
38
.
Note
:
HART Pass-Through requires you to use the HART Pass-
Through license key (FS8KY-6), which provides PlantWeb
®
Smart Remote Automation functionality. This includes the
ability to pass HART data bi-directionally through the network
to AMS
™
Device Manager software.
The module has four input/output channels. The HART-2 module uses
software-configurable switches, which allow you to set each channel as
input or output. When you set a channel as an input, you can configure
it for use in point-to-point or multi-drop mode (which typically connects
to some type of transmitter, such as a temperature reading). When you
configure a channel as an output, it reverts to point-to-point mode
only
.
The output supports a Digital Valve Controller (DVC). Each channel
has analog input capability intended for diagnostic and primary process
variable measurement.
Frequency
Shift Keying
HART superimposes Frequency Shift Keying (FSK) signals on an
analog signal. This technique allows digital information to be passed
to and from the HART device on a 4 to 20 mA analog signal.
Point-to-Point Mode
In
point-to-point
mode, the analog signal is still representative of the
measured variable. This mode allows communications with one
HART device per channel.
Multi-drop Mode
In
multi-drop mode
, you can connect up to five HART devices (in
parallel) to each channel. As with the point-to-point mode, digital
communications are superimposed on the analog signal used to power
the HART devices. Each HART device in multi-drop mode requires 4
mA and the current does not represent any measured variable value.
With all four channels in the multi-drop mode, the ROC800 can
support a maximum of twenty HART devices.
A ROC800 equipped with a HART-2 module is considered to be a
HART Host (primary master) interface with a Class 1 Conformance
classification. The HART-2 module can also be configured with
ROCLINK 800 Configuration software for use as a secondary master in
redundant applications.
Most Universal and some Common Practice commands are supported.
For a list of the commands, refer to the ROC800-Series HART Module
technical specification sheet (
ROC800:HART2
). The supported