www.miinet.com
Moore Industries-International, Inc.
- 111 -
User’s Manual
238-760-00K
May 2019
Functional Safety Dual Input Smart HART® Temperature Transmitter
STZ
SECTION 6
This quality stamp can be one of the following values:
GOOD, BAD, POOR ACCURACY with associated flags HI LIMITED, LOW LIMITED, NOT
LIMITED, CONSTANT
The quality stamps on the sensor readings (SEN1 & SEN2) are used in conjunction with the
input quality alarms to determine the quality of Device Variables and/or the AO response.
Input Quality Alarms
The STZ also allows the user to determine how certain types of input quality issues are handled
and how they can affect the Device Variables and their mapped Dynamic Variables/AO. There
are 3 different quality alarms: Measurement out of Conformance Range, Allow Limited and Allow
Dropping.
Measurement out of Conformance Range [ON]:
When a temperature reading goes outside the
linear conformance range of the sensor and/or when a value is applied to a custom curve outside
the curve’s range (resulting in extrapolation) the accuracy becomes degraded.
If Allow Measurement out of Conformance Range Alarm is set ON (Default), then the Device
Variable will be stamped POOR ACCURACY
If the alarm is OFF, then the Device Variable is stamped as BAD.
Allow Limited [OFF]:
When a sensor’s value reaches its Upper or Lower Limit it will not be
allowed to go beyond the limit. This typically happens in conjunction with input saturation, and/or
RTD/Thermocouple normalization failure.
If Allow Limited is set OFF (Default), then the Device Variable is stamped as BAD.
If the alarm is ON, then it is stamped as POOR ACCURACY / LIMITED.
Allow Dropping [OFF]:
If two sensor inputs are used, the Device Variables which are calculated
from the sensors reflect the quality of the inputs. ie If SEN1 is BAD then the ABDIF would also
be BAD even if SEN2 is GOOD. The exception to this is BU1-2 and BU2-1 which will be GOOD
provided either SEN1 or SEN2 are GOOD quality.
The Allow Dropping allows certain calculated Device Variables (AVG, LOSEL and HISEL) to
maintain the value of the GOOD sensor to provide higher availability of the reading.
If Allow Dropping is ON then the bad sensor data is dropped from the calculated variable and its
quality shall be set to POOR ACCURACY.
If the alarm is OFF (Default) then the derived variable is quality stamped as BAD.
WARNING:
The input quality flags are intended to increase the availability of the system when
using two sensor inputs. However, if SEN1 or SEN2 is directly mapped as the PV and the flags
are set off, a poor accuracy or limited condition will not result in an output fail response. For
SEN1 and/or SEN2, configure a Range Alarm to produce an error or warning when the variable
is outside of its conformance range or upper/lower limit.
