Mitsubishi Electric MELSEC iQ-F FX5 User Manual page 51

■Operation
[Operation performed when an alarm is output]
Digital output values are monitored on the rate alarm alert detection cycle. When a change rate of a digital output value (from
a previous value) is equal to or more than the rate alarm upper limit value, or the rate is equal to or less than the rate alarm
lower limit value, an alert is output as follows.
• Alarm ON (1) is stored in the bit position corresponding to the channel number of 'Warning output flag (Rate alarm upper
limit)' (Un\G38) or 'Warning output flag (Rate alarm lower limit)' (Un\G39).
• 'Alarm output signal' (Un\G69, b8) turns on.
• The ALM LED turns on.
• An alarm code is stored in 'Latest alarm code' (Un\G2). (Page 106 List of alarm codes)
• The A/D conversion on a channel where an alarm was output continues.
• A cycle to output the rate alarm is within 2 ms. When the rate alarm is detected multiple times within 2 ms,
only the first rate alarm detected may be notified as an alert.
[Operation after an alarm was output]
After an alarm was output, if the change rate of a digital output value does not satisfy the alarm output conditions due to being
smaller than the rate alarm upper limit value or being greater than the rate alarm lower limit value, Normal (0) is stored in the
bit position corresponding to the channel number of 'Warning output flag (Rate alarm upper limit)' (Un\G38) or 'Warning output
flag (Rate alarm lower limit)' (Un\G39).
In addition, when all 'Warning output flag (Rate alarm upper limit)' (Un\G38) and 'Warning output flag (Rate alarm lower limit)'
(Un\G39) return to Normal (0), 'Alarm output signal' (Un\G69, b8) turns off and the ALM LED turns off. However, the alarm
code stored in 'Latest alarm code' (Un\G2) is not cleared. To clear the alarm code, turn offonoff 'Error clear request
(Un\G70, b15)' after all the bits of 'Warning output flag (Rate alarm upper limit)' (Un\G38) and 'Warning output flag (Rate alarm
lower limit)' (Un\G39) return to Normal (0).
■Detection cycle
The rate alarm detection cycle is calculated by the following formula.
• Rate alarm detection cycle = Conversion cycle  Setting value of 'CH1 Rate alarm detection cycle setting' (Un\G522)
Ex.
The rate alarm detection cycle under the following conditions
• A/D conversion enable: CH1
• 'CH1 Rate alarm detection cycle setting' (Un\G522): 5 (times)
The rate alarm detection cycle is 400 s (80 s  1 (CH)  5 (times)).
Digital output values are compared in 400 s intervals to check the change rate.
Ex.
The rate alarm detection cycle under the following conditions
• A/D conversion enable: CH1, CH2
• 'CH1 Rate alarm detection cycle setting' (Un\G522): 5 (times)
• 'CH2 Rate alarm detection cycle setting' (Un\G722): 5 (times)
• 'CH1 Averaging process specification' (Un\G501): Count average (2)
• 'CH2 Averaging process specification' (Un\G701): Count average (2)
• 'CH1 Time average/Count average/Moving average/Primary delay filter constant setting' (Un\G502): 100 (counts)
• 'CH2 Time average/Count average/Moving average/Primary delay filter constant setting' (Un\G702): 100 (counts)
The rate alarm detection cycle is 80 ms. (80 s  100 (times) 2(CH) 5 (times)).
Digital output values are compared in 80 ms intervals to check the change rate.
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1 FX5-4AD
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1.4 Functions