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Reference Manual
00809-0100-4052, Rev AA
Section 3: Host Integration
April 2015
Host Integration
registers. Each data point needs a unique Modbus register number, unless they are assigned
different addresses. Register numbers 0-19999 are reserved for Boolean (bit, coil, binary, etc…)
values. Register numbers 20000+ are reserved for floating point or integer values.
Point Name: This is a two part name for the data point. The first part is the HART Tag of the
wireless field device which is producing the data. The second part is the parameter of the
wireless field device.
Point Name is entered as <HART Tag.PARAMETER>. Point Name can be entered using the list of
values (…) or manually entered. The following table gives a list of standard device parameters
which may be considered for Modbus register mapping.
PV, SV, TV, and QV (dynamic variables) will vary by device type. Please refer to the device's
documentation for more information on what value is represented by each dynamic variable.
RELIABILITY and ONLINE relate to wireless communications. RELIABILITY is the percentage of
messages received from the wireless field device. ONLINE is a true/false indication of whether
the device is communicating on the wireless network.
**_HEALTHY parameters are a true/false indication of the health of a particular variable (** =
dynamic variable - PV, SV, etc…). These parameters incorporate critical diagnostics from the
wireless field device as well as communication status.
Note
The **_HEALTHY parameters are a great indication of the health and communications status of
the data values.
State (state value): The value of a data point which drives a Modbus output of 1. For example, if
a data point is reported as either True or False, a state value of True will report a 1 for True and 0
for False. A state of False will report a 0 for True and a 1 for False. State is only required for
register numbers 0-19999 (Boolean, bit, coil, binary, etc…).
Invert: This check box will invert the Modbus output from a 1 to a 0 or a 0 to a 1. Invert is only
used for Boolean values using register numbers 0-19999.
Gain: This value is multiplied to the data value for the purpose of scaling integers. Gain is only
required if scaled is chosen on the Modbus communications page and globe gain and offset is
not chosen.
Table 3-1. Standard Device Parameters for Modbus Register Mapping
Parameter Description Data type
PV Primary Variable 32-bit float
SV Secondary Variable 32-bit float
TV Tertiary Variable 32-bit float
QV Tertiary Variable 32-bit float
RELIABILITY A measure of connectivity to the Gateway 32-bit float
ONLINE Wireless communications status Boolean
PV_HEALTHY Health status for PV Boolean
SV_HEALTHY Health status for SV Boolean
TV_HEALTHY Health status for TV Boolean
QV_HEALTHY Health status for QV Boolean
