Appendix B Troubleshooting
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National Instruments Corporation B-5 FieldPoint FP-3000 User Manual
Block leaves OOS mode but will
not go into the exact TARGET
mode
Your block is correctly configured, but some run-time
condition is keeping the block from reaching its target mode.
• If your block is connected to other function blocks as part
of a Function Block Application, check the status of the
input parameters. If any of these have a quality of Bad or
Uncertain, examine the blocks the inputs came from to
determine the problem.
• If this block is not connected to other function blocks, but
is operating standalone, check the BLOCK_ERR parameter
to determine the problem. If BLOCK_ERR reports Input
Failure or Output Failure, and this is an AI, AO, DI, DO, or
CDO block, there is likely a problem with the I/O channel.
For more information, refer to the section I/O Module
Problems.
The actual mode of a block
switches values A block, such as a PID, may switch modes between IMAN and
AUTO. This means that there is a communications problem
between the PID and the AO blocks.
• Check the schedule. The execution of the PID, A O, and the
communication between them might be scheduled very
close to each other. Space these events further apart and
re-download the configuration.
• Check if the stale limit is set correctly for the loop. If the
block that is subscribing the data is executing at twice the
rate of a block that is publishing data, the stale limit must
at least be set to 2.
PID block output seems incorrect Make sure that you have set the value of the tuning parameters
like RATE, GAIN and RESET correctly.
Recommended values for GAIN, RESET, and RATE are:
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
Table B-3. Generic Software Configuration Problems (Continued)
Problem Solutions