Rate Alarm Function - Mitsubishi Electric MELSEC iQ-R Series User Manual

1.26

Rate Alarm Function

The temperature process value (PV) is monitored every rate alarm alert detection cycle. When the variation from the
previously monitored value is greater than the rate alarm upper limit value or smaller than the rate alarm lower limit value, an
alert occurs. The rate alarm is helpful to monitor the change of the temperature process value (PV) within a limited range.
Rate alarm alert detection cycle = Value (times) set for "Rate alarm warning detection period" of "Rate alarm" in "Application
Setting"  Sampling cycle (500ms/4 channels or 250ms/4 channels)
The temperature process value is judged every rate alarm alert detection cycle with the following formulas:
• (Present value of the temperature process value (PV) - Last value of the temperature process value (PV))  Rate alarm
upper limit value: A rate alarm upper limit alert occurs.
• (Present value of the temperature process value (PV) - Last value of the temperature process value (PV))  Rate alarm
lower limit value: A rate alarm lower limit alert occurs.
Checking the occurrence of an alert
While a rate alarm has occurred, 'CH1 Alert flag' (XC) turns ON and the ALM LED turns on. In 'CH1 Alert definition'
(Un\G401), whether an upper limit alert or a lower limit alert has occurred can be checked. ( Page 230 CH1 Alert
definition)
When an error that makes the ALM LED flash (such as a loop disconnection) has occurred, the ALM LED
flashes.
1 FUNCTIONS
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1.26 Rate Alarm Function