420, Query Unterminated - Keithley 2500 User Manual

Models 2500 and 2502 User's Manual

-420, Query UNTERMINATED

This error occurs when you address the instrument to talk, and there is no response mes-
sage to send. The most likely causes are:
• Not sending a query — You must send a valid query to the instrument before address-
ing 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 2500 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 gener-
ate error -113, Undefined header, and the Model 2500 will discard the second program
message unit :SOUR1:VOLT? even though it is a valid query.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com
Status and Error Messages B-9