GPIB
4-26 370B User Manual
With multiple commands in the message, the message terminator is needed only
once, at the end of the message. Again, most controllers and their languages take
care of this.
Other Messages. Besides receiving commands and queries the 370B can receive
data and send responses to queries. The data and responses can be quite short (a
word and a number) or fairly long (a full set of front panel settings). Measure-
ment information can also be short (a word and a number) or lengthy (a full
display).
ASCII strings. As mentioned before, the only device-dependent messages not
sent as ASCII strings are the binary data used for curves. All other messages,
both to and from the 370B, are ASCII strings made up of numbers or key words
pertaining to the applicable parameters.
Key word messages. A sample, key word exchange resulting in a simple
response is the following.
Query: PST?
Response: PSTATUS BUSY
Another example follows, this one resulting in a more lengthy response.
Query: STP?
Response: STPGEN NUMBER: 5 ,PULSE:OFF,
OFFSET: –1.5,INVERT:OFF, MULT:OFF,
VOLTAGE:2.0E–3
Number message. Numbers other than those representing curves are sent as
strings of ASCII characters. Some controllers may require that these be explicitly
converted to numeric values for use in calculations. Other controllers or
languages may provide a more direct conversion.
Preambles. Preambles are necessary to interpret the numeric information in the
curve data that follows them. Within a preamble, 26 parameters are specified.
The first ten are unique to the 370B curve tracer and are included as a sub-string
linked to the WFID: label. The other 16 parameters include ten that have fixed
values and six that vary with the particular data sent.
Within the WFID: sub-string the parameters are separated by slashes, while the
entire sub-string is delimited by a pair of double quote marks. Most of the
WFID: string is rather strictly defined, with each parameter value being right
justified in a fixed length field. An exception is the BGM value, which may vary
in field length.
The remainder of the preamble uses standard punctuation. A colon links each
parameter label with its corresponding value and the individual label and value
pairs are separated with commas.
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General