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Measurement Definition
Chapter 4
Configuring Temperature Measurements from Dual Output Accelerometers
The temperature signal from a combination acceleration and temperature
(AT) accelerometer is a proportional voltage value. In some cases all that is
required to configure measurements from these values is the calibration factor
(ex. "10 mV/°C"). However, due to variation in the designs of the temperature
circuits of AT sensors, and to the precision measurement capabilities and
sensitivity of the 1444 monitor, it is possible for impedance differences
between sensors to result in temperature measurements that are offset from
actual by several degrees. While this offset has little effect on the accuracy of
the measurement regarding change, it does have to be considered when
configuring the sensor.
The following describes how to configure a 1444 monitor to measure
temperature from AT sensors.
Module Definition - Define Module Functionality Page
Define two channels for the sensor. One must be a Dynamic channel for the
vibration measurement, the other a Static channel, which is used to read the
temperature measurement.
The Dynamix 1444-DYN04-01RA module includes two Analog-to-Digital
Converters. One ADC is connected to channels 0 and 1 and the other is
connected to channels 2 and 3. While the module allows significant
individuality in channel configuration, the rate the ADC samples must be the
same for both channels in the pair it serves. Consequently it can be
advantageous to use the same pair for both vibration and temperature
measurements. Use of both measurements allows greater flexibility to define
the dynamic channels since they then do not share ADC. For example, if two
AT sensors are connected to the module, then wire the vibration signals to
channels 0 and 2, and the temperature signals to channels 1 and 3. As a result,
the sample rate (FMAX) for each of the two vibration channels can be set
independently.
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
165
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