Watlow F4T • 195 • Chapter 5 Function Reference
Temperature Input Errors
Error Status Description
None No error is detected.
Open A sensor is broken or disconnected.
Shorted A sensor has failed or is shorted.
Measurement Error A measurement error has occurred.
Bad Calibration The controller has not been calibrated.
Ambient Error The ambient temperature is outside of the controller's operating range.
RTD Error An RTD sensor error has occurred.
Fail A measurement failure has occurred.
Not Sourced An input signal is not connected to a function block's output.
Stale Data Data sourced from another controller has become unavailable.
Math Error A calculation has no defined result (such as divide by zero).
Thermistor Input
Use this block to condition a temperature measurement made with a thermistor. This FB is
found on the canvas of the FB diagram. The number of these FBs that are available depends
on the number of installed flex modules with thermistor inputs.
The module number shown on the block is the number of the controller’s slot that houses the
flex module with the thermistor input. The Thermistor Input number indicates the specific in-
put on the flex module.
Signals
Direction Label Type Function
Transmitter - - - - Analog The measured temperature with filter and offset applied
This function includes three curves pre-programmed for use with popular sensors selectable
with the Thermistor Curve parameter. See the table. It also can be user-configured for other
sensors by entering the Steinhart-Hart coefficients for the thermistor.
Thermistor Curve
Setting
Resistance @
25°C
Alpha
Technics
Measurement Specialties
(BetaTHERM)
YSI
Curve A 2,252 Ω Curve A 2.2K3A 004
Curve B 10,000 Ω Curve A 10K3A 016
Curve C 10,000 Ω Curve C 10K4A 006
Custom
Use Steinhart-Hart equation coefficients (A, B and C) from thermis-
tor manufacturer corresponding to the terms of the Steinhart-Hart
equation:
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