Mitsubishi Electric MELSEC iQ-R User Manual page 58

Operation
■Operation performed when a warning is output
Digital output values are monitored every rate alarm warning detection cycle. When a change rate of a digital output value
(from a previous value) is equal to or greater than the rate alarm upper limit value, or the rate is equal to or smaller than the
rate alarm lower limit value, a warning is output as follows.
• Alarm ON (1) is stored in 'Warning output flag (Rate alarm upper limit)' (Un\G38) or 'Warning output flag (Rate alarm lower
limit)' (Un\G39).
• 'Warning output signal' (X8) turns on.
• The ALM LED turns on.
In addition, an alarm code is stored in 'Latest alarm code' (Un\G2).
For details on the alarm codes, refer to the following.
Page 165 List of Alarm Codes
The A/D conversion on a channel where a warning was output continues.
■Operation after a warning was output
After a warning was output, if the change rate of a digital output value does not satisfy the warning 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 a bit 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), 'Warning output signal' (X8) 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 on and off 'Error clear request' (YF) 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
Set the rate alarm warning detection cycle in 'CH1 Rate alarm warning detection cycle setting' (Un\G522).
The rate alarm warning detection cycle is the value calculated by multiplying the set value by the conversion cycle.
Ex.
The rate alarm warning detection cycle under the following conditions
• Operation mode: Normal mode (low speed: 20s/CH)
• A/D conversion-enabled channels: CH1 to CH3
• 'CH1 Rate alarm warning detection cycle setting' (Un\G522): 5 (times)
The rate alarm warning detection cycle is 300s. (20s  3 (CH)  5 (times))
Digital output values are compared in 300s intervals to check the change rate.
1 FUNCTIONS
56
1.11 Warning Output Function