Fisher 244EH, 244ER manual Viewing the Process Variable, Intermittent Sensor Algorithm

Viewing the Process Variable

Figure 3-2. Viewing the Process Variable with the 244EC

With version 2.0 and later of the Model 244EC Configuration Interface, users can view the measured temperature (PV) by selecting SERVICE from the menu bar of the main configuration window (see Figure 3-2). In order to view a valid PV, a temperature sensor must be connected to the Model 244E transmitter, and the transmitter must be configured properly for that sensor type. The PV will be automatically updated on the Model 244EC screen approximately two times per second.

244E-244EC01

INTERMITTENT SENSOR ALGORITHM

The electronics of the Model 244E transmitter contains an intermittent sensor algorithm that monitors the input signal during operation. The signal diagnostics routine, which occurs at each temperature update (every 500 milliseconds), eliminates output pulsing in an intermittent open sensor condition. Further, it validates the input signal before the digital-to-analog (D/A) conversion takes place.

If the process temperature changes, the intermittent sensor algorithm causes the transmitter to respond according to one of the three cases described below. Threshold value is the maximum change in reading (as a percentage of output range) within one update cycle (500 ms). The threshold value of the Model 244E is 2% of output range.

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