GPIB
370B User Manual 4-27
A complete preamble might look like this:
WFMPRE WFID:”INDEX 3/VERT 500mA/ HORIZ IV/STEP 2V/OFFSET
0.00V/BGM 250mS/AUX 0.0/ACQ AVG/VCS 12.3/TEXT”
,ENCDG:BIN,NR.PT:3,PT.FMT:XY,XMULT:+1.0E2,XZERO:0,XOFF:
12,XUNIT:V,YMULT:+5.0E–3,YZERO:0,YOFF:12,YUNIT:A,BYT/
NR:2,BN.FMT:RP,BIT NR:10,CRVCHK:CHKSMO,LN.FMT:DOT
Curves. Curve data sets are usually much longer than any other kind. Typically a
set of curve data will be about 4122 bytes long, with most of the bytes being
binary-coded numbers. Thus, most of the string of data is not directly readable,
but must be interpreted by the controller.
An example might look like this.
CURVE CURVID:”INDEX 9”,%NNXXYYXXYY . . . XXYYC
This example breaks down as follows. It starts with an ASCII string of 25
characters:
CURVE CURVID:”INDEX 9”,%
This is followed by a series of binary bytes. The first of these is two bytes giving
the number of data bytes to follow, plus one (typically 4097):
NN
Then come the 4096 data bytes. Each of the 1024 data points on the curve is
represented by four bytes, 2 for the 10 bits of the X coordinate and 2 for the 10
bits of the Y coordinate:
XXYYXXYY . . . XXYY
And finally there is one byte which is the checksum for the preceding 4098 data
bytes.
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General