11.. . APPENDIX A: MASTER ICON REFERENCE
CJC (COLD JUNCTION COMPENSATION) INPUT ICON:
FUNCTION:
Performs the Cold Junction Compensation (CJC) channel selection, amplification, and
Alternatively, the CJC icon can be used to take a resistance reading or measure the temperature of an external thermistor (10Kohm at 25C, Fenwall curve 16 or equivalent). A wire jumper on the terminal strip can be removed and external wiring added if this optional use is desired. Due to the optimization of the CJC circuit for temperature sensing, the resistance measurement capability of this circuit does not provide consistent linearity over the full range. The normal resistance measuring range for a thermistor is 200 ohms to 70,000 ohms.
NOTE: If Thermocouple icons are used in the Program Net, the external sensing function described above must not be used as the temperature of the terminal strip is critical in the calculation of thermocouple temperatures.
INPUTS:
Hardware: No signal input shown on Net for Program Net connections.
Update Clock: Output is updated with new reading upon each Update Clock pulse when Enable input is unconnected or Hi.
Enable: Processing of icon is allowed when Enable pin is unconnected or connected and Enable signal is TRUE.
OUTPUTS:
Output Signal: Data type signal. The Units of the output are degrees C or F, or ohms, selectable from the icon configuration dialog box..
ICON CONFIGURATION DIALOG BOX:
CONFIGURATION OPTIONS:
Icon Name: Specify the name for the channel. This name will show directly under the icon within the Program Net.
Output Name: Specify a name for the Output signal from this icon. This Output Name will be referenced by other icons downstream in the Program Net.
Units: Specifies the temperature scale units that will be output from this icon. Celcius, Fahrenheit, and Ohms are directly supported.
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