Novatech Instruments 408A - Hardware Installation

3
408A Manual
3.0
HARDWARE INSTALLATION
3.1
Power Connection.
Insert 2.5mm plug from
AC-adapter into the receptacle on the rear panel.
The 408A requires a nominal +5VDC. Then plug the
AC-adapter into your AC-line source.
NOTE:
Use only the AC line power adapter provided with
your 408A.
3.2
RS232 Installation.
To use the 408A connect
your host computer to the 9-pin female RS232 con-
nector on the 408A. If you are using a PC, a 9-pin
monitor extension cable used as an RS232 cable will
allow direct connection to the 408A without the use
of a null modem cable or gender changer. If you are
using a different computer, terminal or other control
source, please note that the data
TO
the 408A is on
pin 3; the data
FROM
the 408A is on pin 2 and the
COMMON
return is on pin 5. Set your host to 19.2
kbaud, 8 bits, 1 stop bit, no parity and no hardware
flow control. See Table 2 for RS232 Serial Com-
mands.
3.3 Commands are not case sensitive. There must
be a space after each command except R, CLR, S
and QUE. End with any combination of CR, LF or
CRLF. Illegal commands will result in an error
code being returned per Table 1.
3.4 The “QUE” command returns a string of 80
Hexadecimal (Hex) characters. The characters rep-
NOVATECH INSTRUMENTS
resent the present state of all the registers internal to
the 408A. See Table 7 for the addresses that make up
this string. Note that the frequency will be scaled as
discussed below if an external clock has been used.
3.5 The command in “Bold Italic” ( “B” ) can
cause erroneous operation and must be used with
care. Contact Novatech Instruments for appli-
cation assistance if you feel you need to use this
command, which is intended for “debugging” pur-
poses.
NOTE:
The windows program SOF8 is available from
Novatech Instruments This program provides a
graphical interface for all the commands, allowing
simple serial control of the 408A. A USB-to-Serial
adapter is also available.
WARNING:
Instructions which require the case to be opened
should be performed by a person qualified to do so.
3.6 Internal Clock. If you plan to use the 408A
internal clock, verify that the clock select jumper
wire (W1, see Figure 1) is in the INT position and
that the External Clock Input is left unconnected
(the jumper is a short piece of #28 AWG bare wire).
3.7 External Clock. If you are providing your own
clock source, move the clock select jumper to the
EXT position. Apply your clock to the External
Clock Input BNC. Note that phase noise and stabil-
ity are now dependent upon your supplied clock. See
specifications for signal levels required and accept-
able frequency range.
3.8 The external clock can also be used with Kp=1
for direct connection to the DDS generator. With
Kp=1, the PLL multiplier is disabled. Use this direct
input, up to 300MHz, for optimum phase noise per-
formance.
NOTE:
When using an external clock, frequency scaling of
the “F” command may be required. Please see
Operation, Section 4, for details.
Table 1:
RS232 Error Codes
Error Code
Meaning
OK
Good command received (not sent for
R, CLR and QUE)
?0
Unrecognized Command
?1
Bad Frequency
?2
Bad AM Command
?3
Input line too long
?4
Bad Phase
?5
Bad Time
?6
Bad Mode
?7
Bad Amp
?8
Bad Constant
?f
Bad Byte