Annunciator Dual Sensor Differential Inputs

The annunciator has the ability to use two analog inputs to calculate a differential value on a third input. For example, this setup might be used:
  • AI-1: Discharge Pre-Filter, 0-100 PSI
  • AI-2: Discharge Post-Filter, 0-100 PSI
  • AI-3: Discharge filter differential, -100 - 100 PSI
In this scenario, AI-1 and AI-2 would both be connected to the pressure sensors. AI-3 would not be physically connected to anything, but would calculate the differential value for display, alarms, logging, etc.


A differential input is setup through the following steps:
  1. Set up both "Source" sensors normally.
  2. Both source sensors must have the same type (4-20mA, 1-5V or 0-5V) and range
  3. Select a third analog input for the differential calculation. On this input's setup, select 'Diff' as the sensor type.
  4. The low/high range buttons will change to 'Low Sensor' and 'High Sensor'. The Diff value calculated will be the 'High' sensor - 'Low' sensor. If the 'High' sensor is lower than the 'Low' sensor, the differential will be negative
  5. Alarms, gauges, etc., can be used normally for either or both source sensor and the differential sensor. Alarms are not required for each.

In the above screenshot, AI-7 and AI-8 are used for the source sensors and AI-9 are used for the differential calculation. The physical input AI-9 will be empty in this case since the internal math is using that input for the differential.

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