Tektronix DC 5010 Anleitung Seite 79

Operating Instructions-DC 501 0
The other method that may be used to obtain measure-
ment data involves just "talkingn the DC 5010 and then
reading the results. If a result is available, "talkingn the in-
-- -
strument causes the result to be output. If a result is not
available, it causes the instrument to output an FF(hex) byte
instead. The f~ollowing example shows how to read out data
by just "talking" the instrument and checking for FF(hex).
Both the PIDY? and OPC commands can be used to de-
termine when measurement data is available to be read out.
Data ready status can be queried using the RDY? query
command, as in the following example.
1 0 0 P R I N T 1320: "PER;
"
1 1 0 P R I N T I ? ~ ~ : ~ R D Y ? ; "
1 2 0 I N P U T 1220:A
130 I F K c 0 THEN 1 1 0
1 4 0 I N P U T 1220:A
1 5 0 P R I N T "PERIOD I S " ; A
160 END
The following example shows how the OPC command
allows the Service Request (SRQ) and the Status Byte re-
sponse (STB) to be used to signal data ready.
,--
1 0 0 REPI U S I N G OPC I N T E R R U P T AND
1 1 0 RER STATUS 8YTE T O S I G N A L
1 2 0 REt!
WHEN
THE DATA I S
R E A D Y
1 3 0 CI=O
140 P R I N T C2O:"PEH;OPC ON;"
1 5 0 ON SRQ THEN 2 2 0
1 6 0 WAIT
1 7 0 I F A=O THEN 1 6 0
1 8 0
P R I N T @20:"SEND;OPC
OFF;"
1 9 0 I N P U T i220:A
2 0 0 P R I N T "PERIOD I S ";A
2 1 0 END
2 2 0 POLL D r S Z 2 0
2 3 0 I F S=66 OR S = 8 2 THEN 2 6 0
240 P R I N T "SRQ OCCURED, STATUS
=
" ; S
2513 GO TO 2 7 0
260
A=l
2 7 0
RETURN
Extending Range Using Overflow
Overflow occurs when the internal 43-bit capacity of the
counter is exceeded. By detecting these occurrences of
Overflow, the range of Tmanual and Totalize measurements
may be extended.
The following example monitors a Totalize measurement
watching for the count to reach 1 .OE+ 14, approximately 1 1
times the counting capacity of the DC 5010. This is done by
counting occurrences of Overflow and using this count to
extend the precision of the result.
The next example monitors a Tmanual measurement to
determine when 24 hours have elapsed. Since 24 hours is
equivalent to 86,400 seconds, it exceeds the 27487.8 sec-
onds counting capacity of the DC 5010. By counting the
occurrences of Overflow, the precision can be extended to
count this amount of time.