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Archived: Why Do I Get RIO Scan Interface or Scan Engine Errors when Calling FPGA Reset in RIO 13.0?

This document has been archived and is no longer updated by National Instruments

Primary Software: Driver Software>>NI-RIO
Primary Software Version: 13.0
Primary Software Fixed Version: N/A
Secondary Software: LabVIEW Modules>>LabVIEW FPGA Module

I am using a CompactRIO with the Scan Engine and the NI-RIO 13.0 driver. When I call the FPGA Reset method in my RT code right after opening an FPGA reference or right before running my FPGA I get one of the errors shown below. This also can happen if I open an FPGA reference and then immediately close the FPGA reference without resetting it. Here are some examples:

Open, Reset, Run:

Open reference, immediately close without resetting:

When running my Real-Time code I often get error messages that relate to the RIO Scan Interface or the Scan Engine. Here are some of the error messages I may be receiving:

Error 65700 occurred at an unidentified location

Possible reason(s):

CompactRIO:  Unable to communicate with the module. Reinsert the module and check connections.


Error 65702 occurred at an unidentified location

Possible reason(s):

CompactRIO:  The FPGA personality currently running on the CompactRIO chassis does not support the RIO Scan Interface in this slot.


Error -66431 occurred at an unidentified location

Possible reason(s):

LabVIEW:  The NI Scan Engine terminated due to an internal error.  This is an unrecoverable fault.

These errors do not occur every time I run my VI, and/or they only happen when I deploy a Real-time startup executable. What can I do to eliminate the errors?

These errors occur as a result of a known issue in NI-RIO 13.0. This issue has since been fixed in NI-RIO 13.1. The problem occurs because the Open FPGA VI Reference method has the potential to finish executing on the block diagram before the NI Scan Engine completes its start up process. If you then call the Reset method, the Scan Engine can error out because it gets interrupted during its boot-up process.

Therefore, the best work-around to this problem is to add code that will finish executing when the NI Scan Engine has started. Since all Scan Engine I/O Variables and User-Defined Variables require the Scan Engine to be running in order to return data, you can simply look for errors out of those I/O variables. Here are examples covering the two use cases covered above:

If you are not using any Scan Engine variables you can use a 10 second wait instead. This is a simpler solution, but it is less efficient.

You may be using the Scan Engine without realizing it. If you are using SoftMotion, User-Defined Variables, or any C-series modules in scan interface mode, then your CompactRIO is using the Scan Engine.

Note that if you are getting error -65536 then you should be able to wait for 10 seconds or less and the error will go away. See KB: 5C5BRDN8 Error -65536 When Using Scan Engine and FPGA Simultaneously on a CompactRIO

Related Links:
Product Documentation: Preventing Software Compatibility Issues for CompactRIO Systems
KnowledgeBase 5C5BRDN8: Error -65536 When Using Scan Engine and FPGA Simultaneously on a CompactRIO
Developer Zone Tutorial: Using NI Compact RIO Scan Mode with NI LabVIEW
Developer Zone Tutorial: The RIO Scan Interface Under the Hood


Report Date: 07/31/2013
Last Updated: 09/20/2017
Document ID: 6BUDHNVQ

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