Temperature Conversion Method - Mitsubishi Electric MELSEC iQ-R Series User Manual

1.4

Temperature Conversion Method

This function sets a temperature conversion method for each channel.
Sampling processing
A temperature input module executes the conversion of temperature input values sequentially and stores the converted
values in buffer memory areas as measured temperature values.
The sampling cycle is "Conversion speed  Number of channels where the conversion is enabled". The
conversion speed is 30ms for the thermocouple input module, 10ms for the RTD input module.
Whether to enable or disable the conversion can be set for each channel. Disabling the conversion on unused
channels reduces the sampling cycle.
When two channels (CH1, CH4) for the thermocouple input module are set to be conversion enabled, for
instance, the conversion cycle becomes 60ms (30ms  2).
Averaging processing
A temperature input module performs the averaging processing on measured temperature values for each channel. The
calculated values are stored in the buffer memory areas.
The following three types of averaging processing are provided.
• Time average
• Count average
• Moving average
■Time average
A temperature input module executes the conversion for set time and averages the total value excluding the maximum value
and the minimum value. The calculated value is stored in the buffer memory area.
The number of processing times within the set time varies depending on the number of channels where the conversion is
enabled.
The setting range of the time is 120 to 5000ms for the thermocouple input module, 40 to 5000ms for the RTD input module.
Number of processing times =
Ex.
How to calculate the processing times for the thermocouple input module is shown using the settings in the table below.
Item
Number of channels where temperature conversion is enabled
Setting time
750
*1
= 6.25
(4 × 30)
*1 Values after the decimal point are omitted.
Conversion is processed 6 times and the mean value is output.
The valid lower limit setting value for the time average is calculated by the formula "Minimum processing times
(4 times)  Number of conversion enabled channels  Conversion speed". If the processing times becomes
less than 4 times owing to the invalid setting time, a time average setting range error (error code: 192)
occurs, and the measured temperature value becomes zero.
Setting time
(Number of conversion enabled channels × Conversion speed)
Setting
Four channels (CH1 to CH4)
750ms
1.4 Temperature Conversion Method
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1 FUNCTIONS
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