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Points
Standard point type Use
Accumulator
Container
Standard points have a composite data structure that can represent several field values as
parameters. For example, you only need one analog point for a control loop that maintains the
temperature of an oven, because the point's data structure includes the following parameters
(data items):
Process variable (PV) to record the current oven temperature
n
Output variable (OP) to change the temperature of the oven
n
Set point (SP) to specify the correct oven temperature
n
Mode (MD) to change the loop from manual to automatic control
n
User-defined parameters
You can increase the functionality of a standard point by defining your own parameters to
store custom data. For example, you may want to store a value generated by a script, or
record the serial number of the device associated with the point. You can also add user-
defined scanned parameters to analog and status points so that for example you can retrieve a
collection of related Modbus/TCP Input/Holding Registers or Input Status/Coils
corresponding to a single Modbus/TCP device and Function code. See the topic titled "User-
defined point parameters" in the Station Configuration Guide for more information.
For more information about standard points, see the topic titled "Understanding and
configuring points" in the Station Configuration Guide and 'Building and configuring points'
in the Quick Builder User's Guide.
Data quality
For point parameters values acquired by the server's OPC scan task, the OPC Quality of the
value is also stored. When no OPC Quality is available, Experion sets the quality according to
the following rules.
1. If the value is not a number (NaN), the quality is set to UNCERTAIN.
2. If there is a communications error, the quality is set to BAD with a substatus of Comm
Failure.
3. If neither of the above is true, the quality is set to GOOD.
Honeywell 2017
Totalizer values.
A user-defined point type that allows you to treat a group of related points
as if they were one point.
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