completed implementation of DCPowerSupply class. Everything seems to work. Occasionally, the e3633a generates 420 errors (420 Query UNTERMINATED: The power supply was addressed to talk (i.e., to send data over the interface) but a command has not been received which sends data to the output buffer. For example, you may have executed an APPLy command (which does not generate data) and then attempted an ENTER statement to read data from the remote interface.) However, in debugging this manually, it seems like these errors are not justified.