Stanford Research Systems SR620, Руководство пользователя

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Configuration Menus 19
SR620 Universal Time Interval Counter
the PRINT key is pressed. When set as an output,
the port may be used as an 8 bit digital output port
which is set by the controlling computer. When set
as an input port, the controlling computer may
read the eight bits asserted at the input port.
Printer Port Pin Assignments
Pin Name Function
2 D1 Data bit I/O
3 D2 Data bit I/O
4 D3 Data bit I/O
5 D4 Data bit I/O
6 D5 Data bit I/O
7 D6 Data bit I/O
8 D7 Data bit I/O
9 D8 Data bit I/O
16 -INIT Printer initialization
1 -STROBE Byte output strobe
11 BUSY Printer busy
15 -ERROR Printer error
14 -AUTOFEED +5V via 1 kOhm
17 -25 Chassis ground
The "ScALE" line allows the DVM input ranges to
be fixed to either 2.000 or 20.00 volts full scale.
The default condition allows the DVM's to auto-
scale.
The "JittEr" line is used to select the
representation for the jitter values. Either a
standard deviation (root of the mean squared
deviation, ie. rms) or the root Allan variance may
be displayed.
The "gAtE ScAlE" line will appear in frequency,
period, and count modes. The actual gate time for
a sample is equal to the front panel "gate time"
setting multiplied by the gate scale. For example,
with a gate time of 0.01s and a gate scale of 5E-3
the actual gate time will be 0.01s x 5E-3 = 50ms.
If the gate scale is set to other than the default of 1
the gate time LED will blink. Gate scales ranging
from 1E-4 to 500 allow 1ms to 500s gates.
The "trig ScAle" line allows the setting of the full
scale range of the trigger knobs to either 1.25,
2.50, or 5.00 volts. This allows small trigger levels
to be set more easily. The resolution is 10mV in
all cases. This setting does not affect the trigger
level range over the communications interfaces.
SCAN MENU (Scn)
The SR620 has a scanning capability that allows
automatic measurement of VCO tuning curves,
oscillator step response, etc. The SR620 can, at
the end of each measurement of N points,
automatically step either or both of its d/a output
voltages, and its external trigger delay (see
ARMING section).
The D/A scans allow measurements of timing,
frequency, phase, etc. versus an applied voltage.
(Example: the frequency of a VCO as a function of
Voltage.) The D/A outputs may also be set to fixed
values in the range of +-10 VDC with 5 mV
resolution.
Delay scans allow measurements of timing,
frequency, phase, etc. versus delay from an
external trigger. (Example: the frequency of a VCO
as a function of time after a voltage step is
applied.)
Scan Configuration Menu
Line Default Display Comments
1
ScAn EnA oFF Enable/disable delay and
voltage scans.
2 ScAn PtS 250 Set the number of point
in a scan.
3 hoLd .01 Sec Set dwell time between
points.
4 dA Src chrt chrt Set D/A function: strip
chart or D/A .
5 dA ---.--- ---.--- Set D/A voltage when
configured as D/A
6 SteP ---.--- ---.--- Set D/A step size for
voltage scans.
7 dELAy Scan oFF Enable/disable delay
scans.
8 gAtE-StEP 1E-6 Set gate width and step
size
9 StArt 0.000001 Set delayed gate start
position
The scan menu is used to set and scan D/A
values, gate widths and gate delays from an EXT
input. The scan menu allows one to compose a
graph on an XY scope of a particular
measurement ( frequency, for example ) vs. time
or voltage.
The first line of the scan menu is used to enable
scans. Scans may be turned "oFF" or set to
"SingLE" or "rEPEAt". In the "single" setting the
the SR620 will take one scan and stop. In the
"repeat" mode the SR620 will automatically reset
the scan parameters at the end of a scan and start
another scan. In either mode pressing the
"START" button will take a single scan point, while