HP 436A - Page 39

Operation
Receiving Data Messages (cont'd)
d. Free run
at
maximum rate (R) - this pro-
gramming command is normally used for asynchro-
nous operation
of
the Power Meter.
It
directs the
Power
Meter
to
continuously take
measurements
and
output
data
in the minimum possible time.
It
does
not
allow settling time
prior
to
each
measure-
ment.
e. Free run with delay
(V)
- this program-
ming command
is
identical
to
the
previous com-
mand except
that
it
causes
the
Power Meter
to
exe-
cute a settling-time delay subroutine prior
to
each
measurement.
3-30. When programming
the
Power Meter for
synchronous triggered operation, there are two
factors
that
the
programmer
must
consider
to
ensure
the
validity
of
the
output
measurement
data. The first factor is
the
time
that
it
takes
the
Power Meter
to
respond
to
a full scale change in
input
power level. A typical Power Meter response
curve
is
shown in Figure 3-4.
By
comparing this
curve with
the
measurement timing cycle shown in
Figure 3-5 and summarized
in
Table 3-5
the
'
validity
of
the
Power Meter
output
can be tabu-
lated according
to
operating range and triggering
interval versus change in
input
power level. A gen-
eral summary
of
this information is as follows:
a. When
the
Power Meter is programmed for
trigger with settling time operation, sufficient time
is
provided for
the
Power Meter
to
settle
to
the
in-
put
power level
on
all
ranges
except
Range
1
(most sensitive range).
On Range
1
approximately
10
seconds
(9-10
measurements) are required for
the
Power Meter
to
settle
to
the
input
power level.
Model 436A
b. When
the
Power Meter is programmed for
trigger immediate operation,
the
desired
amount
of
settling time can be incorporated
into
the
program.
3-31. Programming
the
Local
to
Remote Mode
Change. The second factor
that
must
be considered
when programming
the
Power Meter for synchron-
ous triggered operation
is
whether
the
first trigger
is
sent immediately after terminating local opera-
tion.
As
illustrated in Figure 3-6,
the
Power Meter
will
not
respond
to
the first trigger following a
local
to
remote transistion until
it
completes
the
previously initiated measurement and display
cycle. Thus,
the
first
data
output
of
the
Power
Meter may
not
be valid. The options available
to
the
programmer are:
1.
Send
a trigger command (Data Message)
and discount the first
data
output.
Upon
outputting
the
data,
the
Power Meter
will
go
to
Hold and operate synchronously
starting with
the
next
trigger command.
2. Wait approximately 2.5 seconds
after
plac-
ing
the
Power Meter in remote
and
sending
the first program trigger command (Data
Message).
·
3.
Send
a
Clear Message (DCL) immediately
after placing
the
Power Meter
in
remote.
This will restart
the
Power Meter operating
program.
3-32. Sending
Data Messages from
the
Power
Meter
3-33. The
fD
TALK
ONLY
/NORMAL switch
(see Figure 3-3) enables
the
Power Meter
to
func-
EXAMPLE2
(AutoZero)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1
2
3
Remove RF power from power sensor (or set
it
at least
20
dB
below the lowest range
of
the sensor).
{controller talk
and Power Meter
listen},
"Z1T"
Send
zero trigger program codes.
{universal unlisten, controller listen
and Power Meter
talk},{
variable name} Read measured value data from
meter
(characters 4,
5,
6, and 7).
4
If
absolute value
of
measured data
is
not<
2
(0000
± 0002)
then branch
to
step
2;
if it
is,
then continue. (Although
this step averages three seconds, it may take
as
long
as
10
seconds
to
execute.)
5 {controller
talk
and
Power
Meter listen}
,
"9
+DI"
Send
normal measurement mode program
codes.
6 {universal unlisten,
controller listen
and Power Meter talk}
,
{variable name} Read status character (number
0) from
7
3-18
!r:.!)t!)r's
Ol!t:;n~t
<l.?.t?.
c;tTing,
Check status character for an auto zero loop enabled condition (character
0;;;..
decimal 84).
If
loop
is
enabled
then
branch
to
step
5.
If
not, then continue. {This step takes approximately four seconds to execute.)
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