Mitsubishi Electric MELSEC iQ-R Series User Manual page 32

Operation
■Operation performed when an alert is output
Measured temperature values are monitored on the rate alarm alert detection cycle. When a change rate of a measured
temperature 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 'Alert output flag (Rate alarm upper limit)' (Un\G38) or 'Alert output flag (Rate alarm lower limit)'
(Un\G39).
• 'Alert output signal' (XD) turns on.
• The ALM LED turns on.
• An alarm code is stored in 'Latest alarm code' (Un\G2). ( Page 87 List of Alarm Codes)
The temperature conversion on a channel where an alert was output continues.
■Operation after an alert was output
After an alert was output, if the measured temperature value becomes smaller than the rate alarm upper limit value or greater
than the rate alarm lower limit value, Normal (0) is stored in a bit position corresponding to the channel number of 'Alert output
flag (Rate alarm upper limit)' (Un\G38) or 'Alert output flag (Rate alarm lower limit)' (Un\G39).
In addition, when Normal (0) is stored in all the bits of 'Alert output flag (Rate alarm upper limit)' (Un\G38) and 'Alert output flag
(Rate alarm lower limit)' (Un\G39), 'Alert output signal' (XD) turns off and the ALM LED turns off. However, the alarm code
stored in 'Latest alarm code' (Un\G2) is not cleared. Turn on and off 'Error clear request' (YF) to clear the alarm code.
Detection cycle
The rate alarm alert detection cycle is calculated by the following formula.
• Rate alarm alert detection cycle = Conversion speed  Number of conversion enabled channels  Setting value of 'CH1
Rate alarm alert detection cycle setting' (Un\G522)
Ex.
Rate alarm alert detection cycle for the thermocouple input module with the following conditions
• Conversion enabled: CH1, CH2, CH3
• 'CH1 Rate alarm alert detection cycle setting' (Un\G522): 5 (times)
The rate alarm alert detection cycle is 450ms. (30ms  3 (CH)  5 (times))
1 FUNCTIONS
30
1.6 Alert Output Function