User manual

MAUI Oscilloscopes Remote Control and Automation Manual
Block Data
These are binary data values coded in hexadecimal ASCII: four-bit nibbles translated into the digits 0
through 9 or A through F, and transmitted as ASCII characters. They are used only for the transfer of
waveforms from the oscilloscope to the controller (WAVEFORM) and for instrument panel setups (PANEL_
SETUP).
Response Messages
The oscilloscope sends a response message to the controller in answer to a query. The format of such
messages is the same as that of program messages: individual responses in the format of commands,
separated by semicolons ; and ending in terminators (not shown in these examples). These messages can
be sent back to the oscilloscope in the form in which they were received as valid commands.
For example, when the controller sends the program message:
TIME_DIV?;TRIG_MODE NORM;C1:COUPLING?
The oscilloscope might respond with:
TIME_DIV 50 NS;C1:COUPLING D50
The response message refers only to the queries: the TRIG_MODE command is left out. If this response is
sent back to the oscilloscope, it is a valid program message for setting its timebase to 50ns/div and the
input coupling of Channel 1 to 50Ω.
This table outlines syntactical variations between program messages and response messages. The
oscilloscope keeps to stricter rules for response messages than for acceptance of program messages.
Program Response
Uppercase or lowercase characters Always uppercase characters
May contain extraneous spaces or tabs (white space) No extraneous spaces or tabs (white space)
May contain a mixture of short and long command or query
headers
Use short headers by default
Can use COMM_HEADER command to force the oscilloscope
to use long headers, or none at all
Tip: Many drivers set up COMM_HEADER in an Initialization function. COMM_HEADER need only
be set up once, typically in the configuration stage of your application. There may be
programmatic advantages to removing the headers from responses, especially if the return data
will be read into another program.
Waveforms you obtain from the oscilloscope using the query WAVEFORM? are a special kind of response
message. Control their exact format by using the COMM_FORMAT and COMM_ORDER commands.
Whenever you expect a response from the oscilloscope, you must have the control program instruct the
bus to read from the oscilloscope. If the controller sends another program message without reading the
response to the previous one, the response message in the output buffer of the oscilloscope is discarded.
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