When you write your own LabVIEW function (called a "sub-VI"), you might have "error conditions" that you want to signal to the User of your function. For example, you might have a function that attempts to make a connection with an Arduino on COM2, and if it cannot do so within 30 seconds, then you want to inform the User by generating an Error with the message "Cannot connect to Arduino on COM2".
On the "Dialog & User Interface" Palette, there is the "Error Cluster from Error Code" function that you can use to do this. It has (besides Error In and Error Out) four other inputs: Error Code (0), a required input (more on this in the next paragraph); Error Message, a string that you can customize for the particular error; Show Call Chain? (default False), True if you want the Error Message to include where in the Call Chain the error occurred; and Is Warning? (false), True if you want to generate only a Warning.
Error Codes from 5000 to 9999 (and a few other ranges) are for "User-Defined Errors". Error 5002 is in this range, which means that it is defined by the preceding Arduino functions that you called. It has a specific meaning, which you might be able to find, or, if you attach the Arduino Library (possibly as a Compressed (.zip) File) to your Reply to this message, we can help you to find. It may be something as simple as your not specifying a "Required" input, or the Arduino is not connected to the expected COM port.
I don't recall if you said what, specifically, was said in the Error Message. Since it seems to be part of the Arduino package that you are using (whose details I don't know about, so I can't even "go looking for it"), the Error Message parameter might not be present (or not sufficiently detailed), and the "Show Call Chain?" input might have been left in its default, "False", setting, otherwise it would have told you the Arduino function call that caused the Error to appear.
So help us to help you by providing the Arduino library that you are using, or figuring out, yourself, how to "dive into" the Arduino function (if it is not "protected") and find where the Error is being generated, and what causes the Error to appear. Once you know this, you should be able to take steps to prevent the Error from occurring.
Bob Schor
