This FB can only be used with a KTY temperature sensor connected to a voltage input.
Supported platforms: CODESYS 3.5
This FB calibrates measured resistance of a KTY sensor to temperature (°C).
The FB has built-in calibration base curve for KTY sensors, which can be adjusted with two input variables.
The type of used KTY sensor can be selected with i_ResAt25degC input.
This input defines the sensor’s nominal resistance at 25°C temperature and shifts the calibration curve accordingly.
The input i_CalibrationOffset can be used to fine tune the calibration curve.
A KTY sensor can only be used for measuring temperatures between -50°C and 150°C, because of fixed base curve calibration points.
Enabled alarm/warning limits are sanity checked: i_HighAlarmLimit > i_HighWarningLimit > i_LowWarningLimit > i_LowAlarmLimit. Deviation cause parameter error.
The output values o_CalibratedValue and o_Resistance are set to zero if i_Enable is FALSE, or parameter error is diagnosed.
All internal FB initializations are done on the rising edge of i_Enable.
All errors are reset on the rising edge of i_Enable.
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This FB can only be used with a KTY temperature sensor connected to a voltage input. |
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The FB uses internally - S_VoltageToResistance FB from SafeConversion library. - S_ValueDiagnostic FB from SafeDataValidation library. |
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Following parameters are taken into use at the rising edge of i_Enable: - i_ResAt25DegC - i_CalibrationOffset - i_InternalPullUpResistance - i_InternalPullDownResistance - i_HighAlarmLimit - i_HighWarningLimit - i_LowWarningLimit - i_LowAlarmLimit - i_EnableHighAlarm - i_EnableHighWarning - i_EnableLowWarning - i_EnableLowAlarm - i_DiagnosticDelay + Any initialized event code. |
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Input variable name |
Data type |
Range |
Description |
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i_Enable |
BOOL |
FALSE/TRUE |
Enable operation. |
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i_InputVoltage |
DINT |
- |
Measured voltage (mV) of sensor. |
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i_ReferenceVoltage |
DINT |
- |
Measured supply voltage (mV) of sensor. |
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i_ResAt25DegC |
DINT |
- |
Nominal resistance value of the KTY sensor. |
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i_CalibrationOffset |
DINT |
- |
Fine tune offset resistance value (Ohm). |
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i_InternalPullUpResistance |
EPEC_HW. PULL_UP_RESISTANCE |
ENUM |
Internal pull-up resistance of AI input (Ohm). |
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i_InternalPullDownResistance |
EPEC_HW. PULL_DOWN_RESISTANCE |
ENUM |
Internal pull-down resistance of AI input (Ohm). |
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i_HighAlarmLimit |
DINT |
- |
High temperature alarm limit value in °C. |
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i_HighWarningLimit |
DINT |
- |
High temperature warning limit value in °C. |
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i_LowWarningLimit |
DINT |
- |
Low temperature warning limit value in °C. |
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i_LowAlarmLimit |
DINT |
- |
Low temperature alarm limit value in °C. |
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i_EnableHighAlarm |
BOOL |
FALSE/TRUE |
High temperature alarm in use. |
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i_EnableHighWarning |
BOOL |
FALSE/TRUE |
High temperature warning in use. |
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i_EnableLowWarning |
BOOL |
FALSE/TRUE |
Low temperature warning in use. |
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i_EnableLowAlarm |
BOOL |
FALSE/TRUE |
Low temperature alarm in use. |
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i_DiagnosticDelay |
UINT |
- |
Diagnostic delay for alarms and warnings (ms). |
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Output variable name |
Data type |
Range |
Description |
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o_CalibratedValue |
DINT |
- |
Calibrated temperature in °C. |
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o_Resistance |
DINT |
- |
Calculated resistance of the sensor. |
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o_HighAlarm |
BOOL |
FALSE/TRUE |
Calibrated value high alarm status. |
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o_HighWarning |
BOOL |
FALSE/TRUE |
Calibrated value high warning status. |
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o_LowWarning |
BOOL |
FALSE/TRUE |
Calibrated value low warning status. |
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o_LowAlarm |
BOOL |
FALSE/TRUE |
Calibrated value low alarm status. |
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o_ParameterError |
BOOL |
FALSE/TRUE |
Error in input parameters. |
This optional method sets pointer for event code.
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Input variable name |
Data type |
Description |
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i_Enable |
BOOL |
Enable operation. |
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i_pEventCode |
POINTER TO EPEC_DITF.EventCode |
Pointer to signal event code value provided by the application. |
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Pull-up to 5 V is selected in MultiTool Creator's AI configuration when using resistance sensors.
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Example implementation is made with EC44 unit which has pull-up measurement available. For products which does not have AI pull-up measurement (e.g. SL84), use hardcoded 5000 mV value for voltage to resistance conversion's S_i_RefVoltage.
// SL84 does not have pull-up measurements, assume 5V pullup S_TEMP_PULLUP_VOLTAGE: SAFEDINT := DINT#5000; |
Source file topic100748.htm
Last updated 13-Jun-2024
