Philips 6652C - Page 50

Test s numbers 1 .• • 6
6 independent hardware tests ( TS1 •.• TS6) can be
performed
according to the table below.
Test 1 ROM test.
2 RAM test.
3 EAROM test.
4 Measuring logic test.
5 Display test .
6
Te sts 1-5 in sequence.
To perform any test, the nor mal procedure is as
foll ows:
Enable
Service Re q uest (code "SQ1" ) .
Call e.g. test No. 1 (code "TS1").
When SRQ is recognized by the controller a
serial poll is performed and the status byte
is checked to see if the t est was satisfac-
tory. The stat us byte is described in sec -
tion "Status Byte".
Performing the first ste p above is optional. To
speed up the test procedure, skip the first step
and go directly to the second step.
Any running test will be stopped when the con-
troller either reprograms the coun ter or re-
quests measuring data. In th is case the test
wi ll have to be restarted if it is to be comple-
ted.
Trigger mode
When trigged mode is enabled by se nding a "TE1",
the counter will perform only one measurement at
a time. Every individu al measurement must be
trigged by either the GET (Group Execute Trig-
ger) bus command or by sending "X" (ex ecute).
This allows accurate contro l of the start of the
measurement. When "TE0" is chosen (the default
value), the counter is free running, (i.e. as
soon
as one measurement is finished, the next
will start ) .
NOTE: The counter may perform only one measure-
ment
at a time even in the free-running
mode. Thi s is the case when the counter is
an active talker (e .g. caused by an ENTER-
command from HP 85).
Let us cons ider the
following HP 85
program example:
10 OUTPUT 710; "D"
20 ENTER 710; A$
30 PRINT A$
40 END
In line 10 the counter is set to frequency A
measurements (
Default ) and t he me asurement is
started ( TE0 is def aul t ).
S-10
In line 20 the counter is made an active talker
and i nstructed to handshake the result over to
the HP 85. Since the co un ter is free -r unning the
next measurement starts directly.
In line 30 the first result is printed. By now
the second measuring result is ready and dis -
played, b ut since the counter is s till an active
talker it will stop and wait for a handshake
procedure to take place.
In line 40 the program ends so this handshake
will never take place, and the counte r will
have to wait for ever.
Now we might find different values on the coun-
te r 's display and on the HP 85 printer. Th is is
obvious since the pr inted result is the first
measurement and the displayed result is the
second •.
Time-Interval Delay (Programmable Hold Off)
Th e PM 6654C (not the PM 6652, -54 nor PM 6652C)
is capable of measuring single shot time-inter-
vals using the Time -Interval Delay function,
where the delay time can be programmed via the
IEEE-488 bus. This function is thus equvivalent
to the front panel function Hold~Off.
When programming c ommand "HE2" is sent to the
counter, the counter rejects stop -p ul ses for a
time equal to the set Measuring time. HE0
switches off the function.
The Time-Interval Delay range is 100 ~s •.• 99 s .
The accuracy is ±25 ~s ±1 % of set value.
Applicable functions are:
Time interval A-B, single
Single pulse width A
Single rise/fall time A
("F6551")
("F7S51")
("F9SS1")
Example: Time - Interval
1 .5 ms in a
Delay programmed for
single pulse width
measurement:
"F7S51SM1. 5E- 3HE2"
NOTE: Time-Interval Delay cannot be selec te d
together with Hold Off.
HE2 is accessible via the IEEE - 488 bus
only and cannot be
stored in the front
panel menus P1 ..• P8. It is however stored
i n the bus l earn string.
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