According to the manual, 410 is Query Interupted and 420 is Query Unterminated. The first can happen when you send a query but there is still data in the output buffer. If you've requested a certain number of bytes during a read, you probably need to increase that number in order to sure that all data is retrieved. A Device clear command will clear the error. Query Unterminated happens when the instrument is addressed to talk but there is no command pending that will place data in the buffer. The example in the manual cites sending a CONFIG command which doesn't generate data and then doing a read.
Are you using the drivr from NI or have you written your own?
