It's an error from a Scan From String node, which we can't debug without more information. It basically says that it's trying to parse a string to get measurements (or something) but the string doesn't look like what it expected to see.
Open your VI, and look inside it or its subVIs to find the "Scan from string" node that generates the errors. We need to know both what the "format string" and "input string" values are when it generates that error. "Format string" is probably a constant but "input string" you will need to probe while it runs.
Once we figure that out, we can see if maybe your device is replying to the wrong query or something, or if you're trying to parse an empty string and actually have a communications error, or something else.
