Error -2507 occurred at TDMS Write in Database and File IO Posted July 2 · Report reply I'd like to see some probes just to make sure those are the actual values going in, since it might be what you think is going in but isn't. Assuming that is fine I'd check to see if it works on a new file and not one that already exists and has a different data type for that group channel pair. Also the reference is valid obviously, but was it opened as "Open Read-Only"? If this is a subVI I'd just unit test this by writing a quick test that creates a file and writes to the channel. Nothing obvious is wrong with the code you have shown, which makes me think it is an issue somewhere else. Oh and is your timestamp array empty? Or is there an error being generated from that waveform function? I think the TDMS function should just pass the error through but I'd probe it to make sure.