Stanford Research Systems SR620, Руководство пользователя

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18 Configuration Menus
SR620 Universal Time Interval Counter
channels, and to reduce the differential non-
linearity of the analog interpolators. It may be done
whenever the instrument is completely warmed
up, and should be done once a year or after 1000
operating hours. It is recommended that the EXT,
A, and B inputs be disconnected while Autocal is
running.
To run Autocal, allow the SR620 to warm up for at
least 1/2 hour, press the START button in the
SAMPLE SIZE section. This procedure may not be
started until the red CLOCK LED in the CONFIG
section goes off, otherwise a cAL Error 01 will
result. The autocal procedure takes about two
minutes to run, and ends with the message "cAL
donE", then returns to taking measurements. (See
the TROUBLESHOOTING if "cal errors" occur.)
The Autocal procedure may be stopped by
pressing the "reset" key. None of the SR620's
calibration constants are changed until autocal is
complete so stopping in the middle will not affect
the SR620's calibration.
The "cloc SourcE"selects the timebase source.
The up/down buttons may be used to select
between the internal (int) or external (rear)
timebases. If an external timebase is selected,
then the frequency must be specified as either 5 or
10 MHz. When an external timebase is selected,
the SR620 will phase-lock its crystal oscillator to
the external source. If it cannot lock to the external
source, then the red CLOCK LED will turn on in
the CONFIG section. ( This LED is ALWAYS on
for the first few minutes of operation.) Failure to
phaselock may be due to any to the following: (1)
External reference has insufficient amplitude,
stability, or accuracy, (2) the wrong frequency was
specified in the "cLoc Fr" menu, (3) the optional
ovenized oscillator needs to be adjusted to be
within lock range of the external source.
The "cALdAt" line allows the user to adjust the
SR620's 180 calibration bytes provided that the
"cal enable" jumper on the main circuit board is in
the "enable" position. If the jumper is in the
"disable" position this menu line will not appear.
The meaning of these calibration bytes is
described in the CALIBRATION section of this
manual.
OUTPUT MENU (out)
The output menu enables scope displays, selects
the hardcopy device, sets the DVM scales,
chooses a jitter representation, and sets gate and
trigger scales.
Output Configuration Menus
Line Default Display Comments
1
grAPh on Enable scope displays.
2 outPut PrintEr Select Printer or Plotter
for hardcopy.
3 Plot Port rS232 Specify RS-232 or GPIB
for plotter port.
4 PlottEr Addr 5 Specify plotter’s GPIB
address.
5 Pm Port- Print Set printer port mode
6 ScALE Auto Auto DVM #1 and DVM #2
full scale range
7 JitEr Std dEv Specify Standard
deviation or Allan
Variance.
8 GatE ScAIE 1 sets the gate scale
factor
9 trig ScAIE 5.00 sets trigger knobs full
scale range
The scope displays may be disabled by turning
graphs "off" in the first line of the output menu.
Turning the graphs off will reduce the dead time at
the end of a measurement from 60 ms to about 3
ms.
The next line is used to select the hardcopy
device. If a printer is specified as the hardcopy
device, then it must be connected to the
Centronics compatible printer port. The printer
must be an "Epson compatible" printer, with
graphics capabilities. Virtually all printers used
with PC's will suffice. The printer may be
connected to the SR620 with the same printer
cable which is used with a PC.
If a plotter is specified, the plotter may be
connected to either the RS-232 port or the GPIB
port. The port which is used for the plotter must be
specified in the next line of the output menu. The
plotter should be set for 9600 baud, 8 data bits, no
parity, with hardware handshaking using the RS-
232 control lines "CTS" and "DTR" (this is the
default of most plotters). The RS-232
characteristics which are set in the control menu
have no effect on the RS-232 port when used with
a plotter. If the GPIB port is specified for plotter
output, then the plotter's GPIB address must be
set in the next line of the output menu.
The PRINTER PORT may be used as a general
purpose digital I/O port. If a printer is to be used,
then this port should be setup as a printer port. If
the PRINTER PORT is not configured for a printer,
the message "Print diSAbLEd" will appear when