6-12
Section 6: 9100 System Operation — SCPI Language
Final Width = 215mm
6.4.3
Message Exchange
6.4.3.1
IEEE 488.2 Model
The IEEE 488.2 Standard document illustrates its Message Exchange Control Interface model at the detail level required by the
device designer. Much of the information at this level of interpretation (such as the details of the internal signal paths etc.) is
transparent to the application programmer. However, because each of the types of errors flagged in the Event Status Register is
related to a particular stage in the process, a simplified 9100 interface model can provide helpful background. This is shown below
in Fig. 6.1, together with brief descriptions of the actions of its functional blocks.
Response
Formatter
Output
Queue
Message
Exchange
Control
Input
Buffer
Parser
Execution
Control
9100 Functions
and Facilities
IEEE 488.1 bus
Input/Output Control
Bus
Messages
9100 Bus
Transmissions
General and Addressed
Bus Messages
Received
Message
Elements
Parsed
Message
Elements
Executable
Message
Elements
Response
Message
Elements
Response
Data
Requested
Bus Messages
Command
Errors
(CME bit)
Execution
Errors
(EXE bit)
Device-Dependent
Errors (DDE bit)
Query Errors
(QYE bit)
Message
Available
(MAV bit)
Status Byte
(STB)
RQS bit state
for Status Byte
Power On
(PON bit)
(URQ bit)
IEEE-488-1
Bus Interface
Filter out bus management and
configuration commands
Fig. 6.1 9100 Message Exchange Model
