Fluke NORMA 4000 Operators, User Manual, Page: 22 / 184

Remote Control
Users Guide
1-12
Interface
Interface
Input unit
with
input buffer
Output unit
with
output buffer
Data set
Instrument
hardware
Status reporting
system
Command
recognition
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Figure 1-2. Device Model for Remote Control via the Remote Control Interface
Input Unit
The input unit receives commands, character by character, from the interface and stores
them in the input buffer. The input buffer has a size of 2048 characters. The input unit
sends a message to the command recognition when the input buffer is full or when it
receives a terminator, <PROGRAM MESSAGE TERMINATOR>, as defined in IEEE
488.2, or the interface message DCL (GPIB only).
If the input buffer is full, the interface traffic is stopped and the data received up to then
are processed. After this, the interface traffic is continued. If, on receipt of a terminator,
the input buffer is not full, the input unit can receive the next command during command
recognition and execution. Receipt of a DCL (GPIB only) command clears the input
buffer and immediately initiates a message to the command recognition.
Command Recognition
The command recognition analyzes the data from the input unit in the order the data are
received. Only DCL (GPIB only) commands are serviced with priority, whereas GET
commands (Group Execute Trigger, GPIB only), for example, are processed only after
the previously received commands. Each recognized command is immediately transferred
to the data set but without being executed there at once.