Instrument Model And Command Processing - Tektronix MTD200 User Manual

Instrument Model and Command Processing

Input Unit
Command Identification
Data Set and Device
Hardware
MTD200 MPEG Test Decoder User Manual
The instrument model shown in Figure 5–2 has been configured under the aspect
of processing remote-control commands. The individual components operate
independently of each other and simultaneously. They communicate with each
other by means of messages.
Input unit with
RS-232
input buffer
Command
identification
Data set
Device hardware
Output unit with
RS-232
output buffer
Figure 5–2: Instrument model with remote control via RS-232 interface
The input unit receives the commands in the form of characters from the
remote-control interface and collects them in the input buffer. The input buffer
has a capacity of 220 characters. The input unit sends a message to the command
identification as soon as the input buffer is full or as soon as it receives a
terminator as defined by IEEE 488.2.
If the input buffer is full or a terminator is received, data reception is stopped and
the data received so far are processed. Data reception is then continued.
The command identification analyzes the data received from the input unit,
proceeding in the order in which the data are received. Syntax errors in the
command are recognized and passed on to the status reporting system. Following
the syntax test, the range of values of the data is verified and the setting made
accordingly. Only when the command has been completely executed will the
next command be processed by the command identification.
The term "device hardware" refers to that part of the device which performs the
measurement function.
The data set contains all parameters required for setting the device hardware.
Status reporting
system
Remote Control
5–47