XLINK 500/100 Operations & Maintenance Manual page # 95
At this point, M1 = 2.0, Prev1 = 1.0, DeltaT1 = 300
12:15:00 Measurement M1 has made a reading of 3.0
At this point, M1 = 3.0, Prev1 = 2.0, DeltaT1 = 300
Comments can be contained within braces { }. For example:
{convert from degrees Celsius to degrees Fahrenheit} X*9/5+32
Other examples:
SIN(X)+COS(X)+X^3+LOG(X)
(X>1000)*1000 + (X<=1000)*X {would limit the value so that it could
never be greater than 1000}
Troubleshooting:
The only true test of equation processing is to hit Force Measurement after the equation has
been set.
9.4.6.
Equations: Referencing other measurements
If you are setting up an equation that references another measurement, set the measurement
type to meta, and make sure the measurement time and interval are the same as the referenced
measurement. In the equation, reference the other measurements as M1, M2, M3, etc.
If you wish to use the analog reference voltage in the equation, use VREF.
For example, if you wanted to trigger a sampler via the digital output when a conductivity sensor
reading exceeded 80, do the following:
Setup measurement M1 to collect data from the conductivity sensor.
Setup measurement M2 as a Meta measurement, with the Meta Index set to 1 in order
to reference M1. This ensures that M2 will wait for M1 to complete before producing a
result. Make sure the schedule for M1 and M2 is the same.
Setup the equation of M2 to OUTPUT(M1>80, 1, 1, 2000). That will cause the system to
pulse DOUT#1 for 2 seconds whenever the conductivity sensor exceeds 80.
9.5.
Alarm Settings
Alarms are used to send immediate notifications when sensor readings read a certain threshold.
They can also be used to control an output (please see
When a measurement is made, if alarms are enabled for that measurement, the sensor reading is
compared to the
Alarm Threshold
and
Alarm Deadband
. If certain criteria are met, the alarm
triggers (see below).
When a sensor reading reaches a certain threshold, the station is said to
go into alarm.
While that sensor reading stays above the threshold, the system is considered to be
in
alarm.
After the sensor reading drops below the threshold, the system
goes out of alarm
.
When the station is in alarm, it is noted in the station's status.
When a station goes into or out of alarms, the reading causing the alarm is logged. Additionally,
an event is recorded in the log.
