Specifications

Instrument Setups
33
INSTRUMENT SETUPS
The SR400 Photon Counter is a very flexible
instrument capable of many modes of operation.
This section illustrates some of the measurements
that can be made.
DEFAULT SETUP / POWER ON CLEAR
If the STOP key is held down when the power is
turned on, the instrument settings will be set to the
defaults shown below instead of the settings in
effect when the power was turned off.
Menu Line
Setting
COUNT= A,B FOR T PRESET
A= INPUT 1
B= INPUT 2
B SET= 1E3 (inactive)
T= 10 MHz
T SET= 1E0 s (1E7 counts)
N PERIODS= 1
AT N= STOP
DWELL= 1E0 s
D/A= A
D/A RANGE= LOG
DISPLAY= CONTINUOUS
TRIG SLOPE= RISE
TRIG LVL= +2.000 V
A DISC SLOPE= FALL
A DISC= FIXED (∆=+ 0.0 mV)
A DISC LVL= - 10.0 mV
B DISC SLOPE= FALL
B DISC= FIXED (∆=+ 0.0 mV)
B DISC LVL= - 10.0 mV
T DISC SLOPE= FALL
T DISC= FIXED (∆=+ 0.0 mV)
T DISC LVL= - 10.0 mV
PORT1= FIXED (∆=+ 0.000 V)
PORT1 LVL= + 0.000 V
PORT2= FIXED (∆=+ 0.000 V)
PORT2 LVL= + 0.000 V
A GATE= CW (∆=0.000 µs)
A DELAY= 0.000 µs
A WIDTH= 0.005 µs
B GATE= CW (∆=0.000 µs)
B DELAY= 0.000 µs
B WIDTH= 0.005 µs
LCD CONTRAST= 12
STORE= 1
RECALL= DEF
GPIB ADDR= 23
RS-232 BAUD= 9600
RS-232 BITS= 8
RS-232 PARITY= NONE
RS-232 WAIT= 6
RS-232 ECHO= OFF
In addition, the RS-232 termination sequence will
be set to a carriage return and the GPIB SRQ mask
reset to zero.
If the message RECALL ERROR is displayed on
power up without the STOP being held down, then
the instrument is ignoring the setup retained in
memory. This can be due to a low battery. In this
case, the instrument returns to the default setup.
The default setup may also be recalled using the
RECALL menu line or via the remote CL
command or a GPIB DCL or SDC command. In
these cases, the SETUP and COM menus are not
affected.
QUICK CHECK
Unplug all cables from the unit and recall the
default setup by holding the STOP key down
while turning the unit on. The message RECALL
DEFAULT should appear on the display for ~3 s.
Press the DOWN key once to go to the A=INPUT
1 menu line. Rotate the knob until A=10 MHz
appears on the menu line. To start a count period,
press the START key once. The data display
should show counting in counter A for 1 second
and stop at A= 10000000. Counter A will have
counted the internal 10 MHz timebase for 1
second and reached 10,000,000 counts. To reset
the counter, press the STOP key. The data display
should reset to 0.
Now press the DOWN key 3 more times to display
the N PERIODS line. Rotate the knob until N