Instrument Model And Command Processing; Input Unit - R&S AFQ100A Operating Manual

R&S AFQ100A

Instrument Model and Command Processing

The block diagram in the figure below shows how SCPI commands are serviced in the instrument. The
individual components work independently and simultaneously. They communicate with each other by
means of so-called messages.
IEC/IEEE bus
Ethernet
IEC/IEEE bus
Ethernet
Figure 5-1 Instrument model in the case of remote control via IEC/IEEE bus or TCP/IP network

Input Unit

The input unit receives commands character by character from the IEC/IEEE bus or via the Ethernet
and collects them in the input buffer. The input unit sends a message to the command recognition as
soon as the input buffer is full or as soon as it receives a delimiter, <PROGRAM MESSAGE
TERMINATOR>, as defined in IEEE 488.2, or the interface message DCL.
If the input buffer is full, the traffic is stopped and the data received up to then is processed.
Subsequently the traffic is continued. If, however, the buffer is not yet full when receiving the delimiter,
the input unit can already receive the next command during command recognition and execution. The
receipt of a DCL clears the input buffer and immediately initiates a message to the command
recognition.
1401.3084.32
Instrument Model and Command Processing
Input unit with
input buffer
Command
recognition
Data set
Instrument
hardware
Output unit with
output buffer
Status reporting
system
5.23 E-3