Agilent 4294A Read Error

[sobrien]

I'm trying to communicate with the Agilent 4294A over GPIB (GPIB-USB-HS).  I've been using MAX (NI-488.2 Communicator).  When I do a *IDN? everything works fine.  For other commands though I can only do a write and not a query or read.  For example, the "MKRPRM 300HZ" sets the marker correctly during a write, but when I try to query to get back the measurment at that frequency I get an error.  This seems to be the same for every command other than *IDN?  The error is below.

iberr = EABO

EABO indicates that an I/O operation has been canceled, usually due to a timeout condition after a GPIB read.  Before reading from the instrument, verify that the GPIB command you are sending is understood by your device and instructs it to place data in its output buffer.  For information on your device's command syntax, consult the instrument manufacturer's user documentation.

[Dennis_Knutson]

You do not have a basic understanding of instrument communication. In order to do a read, you actually have to send a command that requests the instrument to put information into the transmit buffer. That is what the '?' does. Your example sets the frequency. In order to request  what the current frequency is, you would would do a command such as MKRPM?. The read error you are getting is expected when you have not requested data to be read.

Read again the programming manual of the instrument and maybe do a google search for GPIB/SCPI tutorial.