Mitsubishi Electric MELSEC iQ-F FX5 User Manual page 52

■Judgment of rate alarm
The rate alarm is judged as follows according to the setting of 'Rate alarm change rate selection' (Un\G299).
• When 'Rate alarm change rate selection' is "Rate specification"
The change rate is judged with 'CH1 Rate alarm upper limit value' (Un\G524) and 'CH1 Rate alarm lower limit value'
(Un\G526) converted to digital values per rate alarm detection cycle.
The following shows the conversion formula
Rate alarm upper limit (lower limit)  0.1  0.01  Maximum digital output value
*1 Values after the decimal point are omitted.
Ex.
The judgment value under the following conditions
Setting item
Number of A/D conversion enabled channels
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 and previous digital output values are compared with each other with a rate alarm warning
detection cycle of 400 s (conversion cycle 80 s  5). 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.
Use the following formula to calculate a change rate to be set based on the change amount of voltage and current to detect an
alarm.
Change rate to be set (0.1%) =
*2 Values after the decimal point are omitted.
• When '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 'CH1 Rate alarm upper limit value' (Un\G524) and the 'CH1 Rate alarm lower limit value' (Un\G526).
Alarm occurrence condition
For alert outputting of rate alarm upper limit
For alert outputting of rate alarm lower limit
Ex.
The judgment value under the following conditions
Setting item
Number of A/D conversion enabled channels
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 and previous digital output values are compared with each other with a rate alarm warning
detection cycle of 400 s (conversion cycle 80 s  5 times). From the comparison, it is judged whether or not the increase in
the digital output value is 10000 digits or more, or 3200 or less.
1 FX5-4AD
50
1.4 Functions
*1
of judgment values used for the rate alarm detection.
Change amount of the voltage (current) to detect an alert (V(mA))
Gain voltage (current) (V(mA)) - Offset voltage (current) (V(mA))
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
Setting content
CH1
Rate specification
Sampling processing
5 times
250 (25.0%)
50 (5.0%)
Setting content
CH1
Digital output value specification
Sampling processing
5 times
10000 (digit)
3200 (digit)
*2
× 1000