National Instruments FP-3000 - Manual (Page 52)

Chapter 3 Example Applications
© National Instruments Corporation 3-17 FieldPoint FP-3000 User Manual
Typical values for GAIN , RESET , and RATE are:
Set Alarms
In the above example, it might be convenient to have the FP-3000 generate
an alarm whenever the temperature goes above 40° C. This behavior can be
configured from the PID block or the AI block. This example uses the PID
block.
To set a high limit alarm, follow these steps:
1. Open the PID block and locate the HI_PRI parameter on the Alarms
tab. This is the priority of the high limit alarm.
2. Set the HI_PRI parameter to 2 . Fieldbus alarms can range in priority
from 0-15, with 0 being disabled and 1 meaning that the alarm is
detected but not reported. All other priorities cause the alarm to be
reported.
3. Set the HI_LIM parameter to 40 . This is the high limit that triggers the
high limit alarm. The units are defined to be the same as PV_SCALE ,
which is degrees Celsius.
4. Set up an interface board to receive the alarm. From the NI-FBUS
Configurator, drag the icon that represents your interface card (it might
be named something like “interface0-0”) onto the Function Block
Application Editor window. Connect the Alarms output of the PID to
the Alarms input of the interface card.
5. You must download the configuration because you have changed the
function block application. The PID now detects a high limit alarm
whenever the temperature exceeds 40° C, and the alarm is transmitted
to the interface on your PC. You need a separate program (such as the
Lookout HMI package from National Instruments) to receive, display,
and acknowledge the alarms. You can verify that the alarms are being
detected by the PID block by reading the
HI_ALM parameter. The
Alarm State changes, and the Alarm Timestamp is set when the alarm
goes active.
This concludes the examples. If you want, you can save your example files
by selecting File»Save. Close any open files by selecting File»Close.
GAIN RESET RATE
Pressure control 1.2 3.33 0.8
Temperature control 3.0 25.0 10.0
Flow control 0.33 1.11 0.0
Level control 1.9 16.67 2.7