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Models 8672S/86720A
Operation
3-13. Programming Example and Tips
The example in Table 3-4 sets the Signal Genera¬
tor System to normal pulse modulation at
1000 MHz and +13 dBm:
Table 3-4. Signal Generator System Programming Example
(HP 85F BASIC Language)
18 REMOTE
-?
20 CLERR ''
?
i 9
38 OUTPUT
7
X S
" Q1 8008820
40 OUTPUT
7 x 3
,"010080028
58 OUTPUT
719
;■ "02"
68 OUTPUT 7 28
.
R 0
"
78 OUTPUT 728
''81234
"
88 OUTPUT 728
"80"
99
1 88
OUTPUT
END
O O
i
. a p c a
.*
W.*
<
When programming the Signal Generator System
keep the following points in mind:
a.
The Signal Generator and the FEU must
have different addresses. In the example shown
above, the factory set addresses for the two instru¬
ments are used (719 for the Signal Generator and
728 for the FEU).
b.
When a frequency command is sent to the
Signal Generator that causes the frequency to
cross the 2 GHz boundary between the low and
high band, the command must be sent twice.
Therefore, to avoid confusion, it is recommended
that all frequency commands be sent twice as
shown in lines 30 and 40.
c.
Because the CLEAR command (line 20) can
cause the system frequency to cross the 2 GHz
boundary, it should be used carefully. Refer to the
HP 8672A Operating and service Manual for com¬
plete information on the use of the CLEAR
command.
d.
When the system is operating in the low
band (10 MHz to 2GHz), the LVL UNCALLED on
the Signal Generator lights. This condition will
initiate a service request (pulls SRQ line low). If
the HP-IB controller is monitoring SRQ, it should
initiate a serial poll and check the status byte. The
"level uncalibrated" condition for the Signal Gen¬
erator should be ignored by the system controller
because this is a normal condition when the Sig¬
nal Generator System is operating in the low
band. The SRQ will not be re-initiated unless the
condition is cleared and then reset. Therefore, the
system will not drop into a continuous loop by
keeping the service request active. Refer to the HP
8672A Operating and Service Manual for a com¬
plete discussion of how the Signal Generator
initiates an SRQ.
e.
Both the Signal Generator and the FEU
make a distinction between the letter O and the
number 0 (see lines 50 and 60 in the programming
example). Therefore, be very careful not to inad¬
vertently mix these two characters. However, both
instruments will accept commands in either upper
or lowercase letters.
f.
When the system is returned to local and
then back to remote, the remote vernier setting can
change. To be certain the remote vernier setting is
correct, always re-program the vernier setting
after setting the system to remote operation.
3-14. FEU Remote Operation
The FEU can be operated through the Hewlett-
Packard Interface Bus (HP-IB). Bus compatibil¬
ity, operator's interface checks, programming,
and data format are described in the following
paragraphs.
All front panel functions (except the LINE switch)
are programmable through the HP-IB. In addi¬
tion, some of the functions of the FEU are con¬
trolled by the Signal Generator. Therefore, the
Signal Generator must be programmed using the
appropriate HP-IB command to activate these
functions. For example, the 10 dB step attenuator
is in the FEU but the HP-IB command to set the
attenuator must be sent to the Signal Generator.
The operator's remote checks in Table 3-5 provide
a test of the HP-IB to verify that the FEU can
function with each of the applicable bus messages.
The bus messages are described in Table 3-6.
For more information about HP-IB, refer to IEEE
Std 488, ANSI Std MCl.l, the Hewlett-Packard
Electronic Systems and Instruments catalog, and
the booklet, ''Improving Measurements in Engi¬
neering and Manufacturing" (HP part number
5952-0058).
3-7
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