R3267 Series Spectrum Analyzer Operation Manual (Vol.1)
5.2.5 Message Exchange Protocol
5-11
(5)
Selected Device Clear (SDC)
The SDC message operates in the same manner as the DCL message. However, it is executed only
when the analyzer is a listener. In other cases, the SDC message is ignored.
(6)
Go to Local (GTL)
The GTL message puts the analyzer into local mode. In local mode, all the operations normally
accessible from the front panel are available.
(7)
Local Lockout (LLO)
The LLO message puts the analyzer in the local lockout mode. If the analyzer is set to the remote
mode when this is done, all operations normally available from the front panel are disabled (note
that in the normal remote mode, you can perform front panel operations using the LOCAL key).
You can use one of the following three methods to set the analyzer to local mode from the local lock-
out mode:
•
Send a GTL message to the analyzer
•
Set the REN message to false (the local lockout mode will be canceled)
•
Turn the analyzer power off and on again
5.2.5
Message Exchange Protocol
The analyzer receives program messages from controllers or other devices through the GPIB bus and gen-
erates response data. Program messages include commands, queries (commands used to query response
data) and data. The procedure used to exchange these commands, queries and data is explained in this sec-
tion.
(1)
GPIB Buffers
The analyzer is equipped with the following two buffers:
(a) Input Buffer
The input buffer is used to store data temporarily for command analysis (it has a length of 1024
bytes so an input larger than this is ignored.)
Use either of the following two methods to clear this buffer:
•
Turn the analyzer power on.
•
Execute DCL or SDC.
(b) Output Buffer
The output buffer is used to store data which is going to be read from the controller (1024 bytes).
Use either of the following two methods to clear this buffer:
•
Turn the analyzer power on.
•
Execute DCL or SDC.
