Annunciator Input Calibration

Overview

In most cases, Brain (annunciator) inputs should not need to be calibrated. Calibration may be needed though for very high precision operations or if physical factors affect sensor readings. With DCT version 1.35.113 and annunciator version 1639 (or higher) thermocouple and analog inputs can be calibrated. EIM v2.26 added the same screen.

Calibration Setup Screen

After entering Engineering Access level, Navigate to Settings -> Brain -> Inputs Setup -> Input Calibration to access the calibration screen.

For each thermocouple or analog input, there is an offset and span value that can be adjusted.

When an input is read, the reported value will be:

(Reported Value) = (Read Value) * Span + Offset

By default, the offset is 0 and the span is 1 which causes no change to the reading. Sometimes only an offset will be needed, which adds that value (which can be negative) to any reading. A worksheet is available to help determine the offset/span from two sample points.

The offset / span is operated against displayed units. E.g. if a pressure reading is in PSI, then an offset of 10 will lift the value by 10 PSI.