A-8 Return to Section Topics 6482-901-01 Rev. A / August 2012
Appendix A: Status and Error Messages Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual
expects line-feed with EOI as the terminator. See the reference manual for your particular
IEEE-488 interface.
-420, Query UNTERMINATED
This error occurs when you address the instrument to talk, and there is no response message to
send. The most likely causes are:
• Not sending a query: You must send a valid query to the instrument before addressing it to
talk.
• Sending an invalid query: If you have sent a query and still get this error, make sure that the
instrument is processing the query without error. For example, sending an ill-formed query
that generates an error -113, Undefined header and then addressing the instrument to talk
will generate an error -420, Query UNTERMINATED as well.
• Valid query following an invalid command: This situation can occur when you send multiple
commands or queries (program message units) within one command string (program
message). When the Model 6482 detects an error in a program message unit, it discards all
further program message units until the end of the string; for example:
:SENS1:DATE?; :SOUR1:VOLT?
In the above program message, the program message unit :SENS1:DATE? will generate
error -113, Undefined header, and the Model 6482 will discard the second program
message unit :SOUR1:VOLT? even though it is a valid query.
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