Emerson 1552WU Reference Manual page 24

Section 3: Host Integration
April 2015
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.
Table 3-1. Standard Device Parameters for Modbus Register Mapping
Parameter
PV
SV
TV
QV
RELIABILITY
ONLINE
PV_HEALTHY
SV_HEALTHY
TV_HEALTHY
QV_HEALTHY
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.
18
Description
Primary Variable
Secondary Variable
Tertiary Variable
Tertiary Variable
A measure of connectivity to the Gateway
Wireless communications status
Health status for PV
Health status for SV
Health status for TV
Health status for QV
Reference Manual
00809-0100-4052, Rev AA
Data type
32-bit float
32-bit float
32-bit float
32-bit float
32-bit float
Boolean
Boolean
Boolean
Boolean
Boolean
Host Integration