Mitsubishi Electric Melsec Q Series User Manual page 32

4 Functions
(2) Behavior of the upper/lower limit alarm
1) When the alarm reset method is in the "self-retention" setting (example of an upper limit
monitoring at alarm 1)
(a) If the measured value that was set with the alarm 1 monitoring item exceeds the upper
limit and the situation continues and remains for the alarm 1 delay time, Alarm 1 flag (XnA)
will turn ON. At the same time, ALM1 LED flashes.
(b) Even if the measured value goes below the upper limit, Alarm 1 flag (XnA) retains an ON
status (self retention). During the self-retention, ALM1 LED is turned on.
(c) By turning Alarm 1 reset request (YnA) to ON, Alarm 1 flag (XnA) will turn OFF. At this
time, ALM1 LED is turned off.
(d) Check that Alarm 1 flag (XnA) becomes OFF, and then set Alarm 1 reset request (YnA) to
OFF.
Alarm 1 flag (XnA)
Alarm 1 reset request (YnA)
Figure 4.2.4-2 Time chart of the upper/lower limit alarm (alarm reset method = "self-retention")
2)When the alarm reset method is in the "auto reset" setting (example of an upper limit
monitoring at alarm 1)
(a) If the measured value that was set with the alarm 1 item exceeds the upper limit and the
situation continues and remains for the alarm 1 delay time, Alarm 1 flag (XnA) will turn ON.
At the same time, ALM1 LED flashes.
(b) If the measured value goes below the upper limit, Alarm 1 flag (XnA) will turn OFF. At this
time, ALM1 LED is turned off.
(c) If the measured value that was set with the alarm 1 monitoring item exceeds the upper
limit but goes below the upper limit within the alarm 1 delay time, then Alarm 1 flag (XnA)
will remain in the OFF status.
Alarm 1 flag (XnA)
Figure 4.2.4-3 Time chart of the upper/lower limit alarm (alarm reset method = "auto-reset")
Upper limit
Alarm delay time
OFF Flashing
Upper limit
Alarm delay time
OFF Flashing
ON OFF
Alarm delay time
OFF
4 - 14
QE81WH