Stanford Research Systems SR780, Operating Manual And Programming Reference

Page: 459 / 497

Data Transfer Commands 5-93
SR780 Network Signal Analyzer
Each complex point is two floating point numbers, representing the real and
imaginary parts. Thus, the TLOD command loads 2n floating point numbers (4-
byte IEEE floats).
The downloaded values are assumed to have the same units as the target trace.
Depending upon the trace measurement, the values are assumed to be either
unitless, Volts or Volts
2
.
Trace Measurement Units
FFT
V
Time V
Coherence unitless
Cross Spectrum V
2
Transfer Function unitless
Orbit V
Correlation V
2
UserFunction unitless
Octave V
2
Swept Sine V
The download sequence is as follows:
Host
Send TLOD ? i, n. Do NOT wait for IFC to be set in the Serial Poll status.
SR780
Checks to make sure that Trace i has length n. Returns 1 (4-byte binary long int)
if OK to begin data transfer. A return of 0 indicates that n is too large for Trace i.
Host
On receipt of 1 (4-byte binary long int), executes a binary transfer to the SR780
of 2n 4-byte IEEE floats. The order is real part of point 0, imag part of point 0,
real part of point 1, imag part of point 1, etc. Each 4-byte float is transmitted least
significant byte first. A total of 8n bytes are transferred. Assert EOI with the final
byte of the transfer.
Serial Poll until IFC (bit 7) is set in the Serial Poll status before sending another
command.
TASC ? i, n
The TASC command loads ASCII data into Trace i. The parameter i selects
Trace 1 through 5. This command is valid only via the GPIB interface.
The target Trace i must already store data of the measurement type and length to
be loaded from the interface. The loaded data simply takes the place of the stored
trace data and assumes the measurement parameters (Measurement, Averaging,
Window, Frequency span, etc.) and length of Trace i.
TASC loads the actual complex data values in the trace, NOT the data displayed
in a particular view. Remember, views are simply different ways of showing the
actual complex data.