Novatech Instruments 408A - Page 4

NOVATE
CH INSTRUMENTS
4
408A Manual
Table 2:
RS232 Serial Commands
RS232 Command
Function
F0 XX.XXXXXXXXXXXX
Set Frequency in MHz to nearest 1
µ
Hz. Decimal point required.
F1 XX.XXXXXXXXXXXX
Start Frequency in MHz to nearest 1
µ
Hz. Decimal point required. Same as F0 if Mode 0 is
selected.
F2 XX.XXXXXXXXXXXX
Stop Frequency in MHz to nearest 1
µ
Hz. Decimal point required. Modes 1 and 2.
Fd XX.XXXXXXXXXXXX
Delta Frequency in MHz. Software sets to nearest 1
µ
Hz. Decimal point required.
E x
x=D for Echo
D
isable, x=E for Echo
E
nable
Q x
x=D for Q-channel
D
isable, x=E for Q-channel
E
nable
R
Reset. This command resets the 408A. EEPROM data is preserved and, if valid, is used upon
restart. This is the same as cycling power.
CLR
Clear. This command clears the EEPROM valid flag and restores all factory default values.
Px N
Set Phase. N is an integer from 0 to 16383. Phase is set to N*360
o
/16384 or N*
π
/8192 radi-
ans. Sets either the phase P1 or P2 depending upon the value of x (1 or 2). The I and Q out-
puts are always nominally 90
o
. In Mode 0, this sets the static phase. In Mode 4, the phase is
either P1or P2 depending upon the state of Pin 8 of the parallel connector.
A x
x=E for ACMOS/TTL
E
nable, x=D for ACMOS/TTL
D
isable
S
Saves current state into EEPROM and sets valid flag. State used as default upon next power
up or reset. Use the
“CLR”
command to return to default values.
QUE
Return present frequency, phase and status. Returns an 80-character string of all internal set-
tings: hexadecimal format. See Table 7.
M N
Mode command. N is 0, 1, 2, 3 or 4. 0 is Single Tone, 1 is FSK (pin 8 of parallel port is
active), 2 is Triangular Ramped Frequency, 3 is Chirp Frequency and 4 is BPSK (pin 8 is
active). Defaults to Mode 0 upon turn-on, unless another mode is saved. See Appendix A.
Td N
Time at each Fd (see Appendix A). N is an integer from 0 to a maximum value of 2
20
-1 or
1048575. Applies to modes 2 and 3 only. Approximately 3.5ns increments using internal
clock. In mode 2, frequency ramps from F1 to F2 and returns to F1 continuously in steps of
Fd at time intervals of Td.
Tr N
Repeat time in mode 2 and 3. In mode 3, the frequency will ramp starting at F1 in steps of
Fd, at time intervals Td, until Tr times out, repeating continuously from F1. N is an integer
between 5 and 2
32
-1 (4294967295). Approximately 7.0ns increments with the internal clock.
A 3.3V CMOS level pulse at the start of each ramp is provided on Pin 10 of the parallel I/O
connector. Approximately 40ns (8 system clocks) wide for the internal clock. In Mode 2, Tr
sets the timing of an external trigger pulse on Pin 10 of the parallel interface.
Vx N
Set voltage level of output. In default, the amplitude is set to the maximum: approximately
+7dBm into 50
Ω.
N can range from 0 (off) to 4095 (no decimal point allowed). Voltage level
is scaled to N/4096. x is I or Q to set the amplitude on the I or Q channel. If N >4095, the
scaling is turned off and both outputs are set to maximum. Overrides the
“Z”
command.
Kp aa
Set PLL reference multiplier constant. Must be one Hex byte as two characters. Legal
values are 1 (bypass PLL) and 4 to 20 ( 01
h
, 04
h
to 14
h
).
Z N
Turns on 30% Amplitude Modulation of Cosine (I) channel output. N is the frequency of
modulation in 100Hz steps, 900Hz maximum (9). N = 0 turns off modulation. Use of this
command overrides the V command on the I channel. Entering any
“M”
command turns off
modulation.
B aadd
Set a data byte
“dd”
at address
“aa”
in Hex. Allows setting of all internal registers.
“aa”
is in the range of 00
h
to 27
h
while
“dd”
is from 00
h
to ff
h
. No error checking, other then
correct format, is performed. It is possible to set the 408A into a nonfunctional state requiring
a power cycle to recover with this command. Some internal modes may require excessive
power and may permanently damage the 408A (for debugging).