Tektronix 2714, Programmer'S Manual

Page: 111 / 308

Command and Query Definitions
2714 & 2715 Programmer Manual
4–25
CURve<space><ind><bc
hi
><bc
lo
><d
1
><d
2
>...<d
512
><checksum>; where:
CURve Command header
space Header delimiter
ind Absent when ASCII-encoded decimal is used; equals #H when ASCII-en-
coded hexadecimal is used; equals the % sign when binary is used
bc
hi
High order byte of the number of data points (always 512) plus one in the
data block: absent in decimal, 00000010 in binary, 02 in hexadecimal
bc
lo
Low order byte of the number of data points (always 512) plus one in the
data block: absent in decimal, 00000001 in binary, 01 in hexadecimal
d
1
d
2
...d
512
1
st
data point, 2
nd
data point,...512
th
data point of the curve; each data point
may be represented by one to four bytes depending on encoding:
H
Binary: one byte
H
Hexadecimal: two bytes representing the hexadecimal numerals 0–F
H
Decimal: two to four bytes representing a comma delimiter plus one to
three decimal numerals 0–9
checksum Absent for ASCII-encoded decimal; otherwise:
H
2’s complement of {[Sdi + bchi + bclo ] MOD 256}
Figure 4–1: Format of Curve Data
Figure 4–1 shows the format of curve data. The checksum definition ensures that
the sum (modulo 256) of the data points plus point count plus checksum equals
zero.
Here are several more points worth noting about the various encodings:
H
Binary encoding uses one byte per data point making it more compact and
faster than the other techniques.
H
Hexadecimal always uses two bytes per data point. Thus it requires no
delimiter to separate the points.
H
Decimal uses a variable number of bytes (1 to 3) to encode each data point,
and therefore requires a data point delimiter (the comma).
H
The use of delimiters in decimal encoding makes this form compatible with
many spread sheets and word processors. This enables you to create custom
waveforms for later transmission to the spectrum analyzer, or to edit
waveforms previously returned from the spectrum analyzer.