Mitsubishi Electric MELSEC iQ-F FX5 User Manual page 360

■Judgment of rate alarm
The judgment of the rate alarm is judged by the following formula according to the rate alarm change rate selection and input
type setting.
• When the rate alarm change rate selection is "rate specification"
Convert 'CH1 rate alarm upper limit value' (Un\G524) and 'CH1 rate alarm lower limit value' (Un\G526) to digit value for each
rate alarm warning detection cycle value. The following shows the conversion formula of judgment values used for the rate
alarm detection.
Input type
Case of current or voltage
Case of resistance temperature
detector, and thermocouple
*1 When the input type is "current" or "voltage", set it in units of 0.1% with respect to the width (gain value - offset value) of the analog input
range.
When the input type is "RTD" or "Thermocouple", set it in units of 0.1% with respect to (maximum value - minimum value) of measured
temperature value.
Ex.
The judgment under the following conditions
Setting item
Conversion enabled channels
CH1 Input type/range setting
Rate alarm change rate selection
CH1 Average processing specification
CH1 Rate alarm alert detection cycle setting
CH1 Rate alarm upper limit value
CH1 Rate alarm lower limit value
In the above case, the current digital output value and the previous digital output value (digital output value of 5 ms before) are
compared at each rate alarm warning detection cycle of 5 ms (1 ms  5 times). As a result of the comparison, it is judged
whether the increase of the digital output value is 8000 (= 250  0.1  0.01  32000) digit or more or 1600 (= 50  0.1  0.01 
32000) digit or less.
• When the rate alarm change rate selection is "Digital output value specification"
It is judged by comparing the difference between the current digital output value and the digital output value in the previous
detection cycle with the rate alarm upper limit value and the rate alarm lower limit value.
Alarm occurrence condition
For alert outputting of rate alarm upper limit
For alert outputting of rate alarm lower limit
*1 When the input type is "RTD" or "Thermocouple", set the rate alarm upper limit (lower limit) in unit of 0.1.
Ex.
The judgment under the following conditions
Setting item
Conversion enabled channels
CH1 Input type/range setting
Rate alarm change rate selection
CH1 Average processing specification
CH1 Rate alarm alert detection cycle setting
CH1 Rate alarm upper limit value
CH1 Rate alarm lower limit value
In the above case, the current digital output value and the previous digital output value (digital output value of 200 ms before)
are compared at each rate alarm warning detection cycle of 200 ms (40 ms  5 times). From the comparison, whether the
increase in the digital output value is 10000 (1000.0) or more, or 3200 (320.0) or less is judged.
3 FX5-8AD
358
3.4 Functions
Conversion formula
Rate alarm upper limit (lower limit)
Rate alarm upper limit value (lower limit value)
value of digital output value)
Conversion formula
Current digital output value - Digital output value at the previous detection cycle  Rate alarm upper limit value
Current digital output value - Digital output value at the previous detection cycle  Rate alarm lower limit value
*1
 0.1  0.01  Maximum value of digital output value
*1
 0.1  0.01  (upper limit value of digital output value - lower limit
Setting content
CH1
Current (4 to 20 mA)
Rate specification
Sampling processing
5 times
250 (25.0%)
50 (5.0%)
Setting content
CH1
Pt100
Digital output value
Sampling processing
5 times
10000 (1000.0)
3200 (320.0)
*1
*1