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RT Fieldpoint Read Error causes execution to stop

The Fieldpoint read functions behave differently when run on a PC in labview or embedded on an RT target.  On a pc, if you try to read data for the first time from a module that is offline, the read functions just returns an error.  If you try this same thing on an RT target, the code stops executing.  This seems like a huge problem.  If you have an RT target that reads data from 5 different FP banks and one of them is offline when you startup, the code just quits. 
 
If the bank goes offline after at least one read has been completed, then the read function returns an error.  (this behave just like it does on a standard pc).
 
How can I work around this.  This seems like a very serious problem!  The code should continue to execute and relay the error, not just abort!!!!!
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Message 1 of 14
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Are you trying to read from a module on the same backplane as the RT controller, or is it remote?  If remote is the controller communicating with a serial or an ethernet connection?

What version of LabVIEW RT and Fieldpoint do you have?  You can determine this by going to Program Files>>National Instruments>>Measurement and Automation.  Under the remote systems, find your Fieldpoint unit and expand the software tab.  If you have a much older version of Fieldpoint, you would need to go to Fieldpoint Explorer.
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Message 2 of 14
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I am using an FP-2015 to read data on two remote systems (each having an FP-1601 as a controller).  I am using ethernet communication.  I am using Labview 8.21 and RT 8.21. 
 
When running the code on my RT target, if one of the two remote systems is offline the first time the code on the FP-2015 executes, when the code reaches the first FP read VI, the codes stops executing.  It doesn't return an error, it just stops executing, this is a terrible behavior . If the module is present the first time it goes to read, and then at some point later gets disconnected, the FP read returns an error rather than stopping execution of the code.  AS LONG AS THE FIRST TIME I GO TO READ DATA FROM A MODULE, THE MODULE IS PRESENT, THEN THE FP READ RETURNS AN ERROR IS THE MODULE IS LOST.  BUT IF THE FIRST TIME YOU GO TO READ IT IS NOT THERE, CODE STOPS EXECUTING.
 
This is not the same behavior which occurs if you use the FP read function on a standard PC.  Whether it is the first time or the one milliionth time you go to read data from a FP module that is offline, it just returns an error. 
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Message 3 of 14
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gt8860a, sorry for the delay.  I have reproduced this issue with a cFP-2020 as the target and a cFP-1808 as the network module to read from.  If I disconnect the network cable to the 1808 and run my code with highlight execution, it stops at the read.  It looks like this is universal to Fieldpoint considering the differences in our setups.

I will file a CAR on this.  Thank you for pointing this out.
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Message 4 of 14
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Developers have informed me that this is currently expected behavior because certain files were lost on the embedded side.  These files allow the functionality that we see on the development side.  I have created a product suggestion for a warning message.
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Message 5 of 14
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Thanks for looking into it Trey.  Sounds like we will have to just deal with this until a newer Fieldpoint driver is written.  I find it amusing that the developers refer to this as expected behavior. 
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Message 6 of 14
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Hi gt8860a,

Thanks for your feedback.  If you are interested in seeing this feature, please submit a product suggestion here.  The reason we identify this as expected behavior is that the developers had made the decision not to include this feature at the time of development. 

If you submit a product suggestion along with Trey's, we'll be sure to re-evaluate this feature when we are in the development stage for the next FieldPoint Driver release, but we cannot guarantee that this feature will be included.

Please let me know if you have any further questions or concerns.

Regards,
Ching P.
DAQ and Academic Hardware R&D
National Instruments
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Message 7 of 14
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Thanks for your reply Ching.  What would you recommend as a workaround?
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Message 8 of 14
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This really sounds like a bug to me.  If you had a VISA serial read command and didn't get a response back in a timely manner, a timeout error would be raised.  It wouldn't just stop the code dead there.  It sounds like on the PC, the FP read code functions properly as an error gets raised if the read can't be completed.  Then it is up to the programmer to do what is necessary to work around that error.  But on the RT system the code just halts?  How can you be expected to work around that?
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Message 9 of 14
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Hi gt8860a,

I apologize, there was some confusion as to what the issue is.  I do not believe that the real-time target should disconnect in this situation.  I still have the Corrective Action Request open, and will get back to you after I have some time to investigate further.

In the mean time, please let me know if you have any additional questions or concerns.
Regards,
Ching P.
DAQ and Academic Hardware R&D
National Instruments
Message 10 of 14
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