Keithley 2520, User Manual, Page: 261 / 329

B-8 Status and Error Messages Model 2520 User’s Manual
• Incorrectly configured IEEE-488 driver. The driver must be configured so that
when talking on the bus it sends line-feed with EOI as the terminator, and when lis-
tening on the bus it 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 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 UNTERMI-
NATED" 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 2520 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:CURR?
In the above program message, the program message unit :SENS1:DATE? will generate
error -113, "Undefined header", and the Model 2520 will discard the second program mes-
sage unit :SOUR1:CURR? even though it is a valid query.