Yokogawa PC-Based MX100 - Manual (Page 19)

1-10 IM MX100-01E
Alarms
This function outputs alarms when measured or computed values* meet certain
conditions. Select up to four alarms of the following six types on each channel.
• Upper limit alarm
Generates an alarm when the measured or computed value* is greater than or equal
to the alarm value.
• Lower limit alarm
Generates an alarm when the measured or computed value* is less than or equal to
the alarm value.
• Differential upper limit alarm
Generates an alarm when differential input values (difference between the measured
value of a channel and that of the reference channel) are greater than or equal to the
alarm value.
• Differential lower limit alarm
Generates an alarm when differential input values (difference between the measured
value of a channel and that of the reference channel) are less than or equal to the
alarm value.
• Upper limit on rate-of-change alarm*
Generates an alarm if the amount of change in the computed value in the rising
direction exceeds the alarm value within the rate-of-change detection interval.
• Lower limit on rate-of-change alarm*
Generates an alarm if the amount of change in the computed value in the falling
direction exceeds the alarm value within the rate-of-change detection interval.
* When using computed value alarms, do not disconnect the MX100 and the PC software.
Alarms will not occur because the Computation function will not work on the MX100 by itself.
Alarm Value Hysteresis
You can set a width (hysteresis) to the values used to activate and release alarms. Alarm
hysteresis can prevent frequent activation and release of alarms when the measured
value is unstable around the alarm value.
Alarm
setting
Alarm release
Measured vale
Alarm activated
Upper limit alarm Lower limit alarm
Measured value
Alarm release
Hysteresis
Alarm setting
Alarm activated
Alarm Output Timing
Alarms occur at each measurement interval based on the alarm settings. However when
the measurement interval is 10 or 50 ms, alarms occur at 100 ms intervals based on all
of the data.
1.2 Main Module Functions