High-Speed Transfer From Memory - Agilent Technologies 3458A User Manual

10 OPTION BASE 1
20 INTEGER Num_readings
30 INTEGER Int_rdgs(l:30000) BUFFER
40 REAL Rdgs(l:30000)
50 Num_readings=30000
60 ASSIGN @Dvm TO 722
70 ASSIGN Int_rdgs TO BUFFER Int_rdgs(*)
80 OUTPUT @Dvm; "PRESET FAST"
90 OUTPUT @Dvm;"APER 1.4E-6"
100 OUTPUT @Dvm; "OFORMAT SINT"
110 OUTPUT @Dvm; "NRDGS"; Num_readings
115
120 TRANSFER @Dvm TO @Int rdgs;WAIT
121 !INTEGER ARRAY; SINCE THE COMPUTER'S INTEGER FORMAT IS THE SAME AS
125 !SINT,NO DATA CONVERSION IS NECESSARY HERE (INTEGER ARRAY REQUIRED)
130 OUTPUT @Dvm; "ISCALE?"
140 ENTER @Dvm;S
150 FOR I=1 TO Num_readings
160 Rdgs(I)=Int_rdgs(I)
165!FORMAT (NECESSARY TO PREVENT POSSIBLE INTEGER OVERFLOW ON NEXT LINE)
170 R=ABS(Rdgs(I))
180 IF R>=32767 THEN PRINT "OVLD"
190 Rdgs(I)=Rdgs(I)*S
200 Rdgs(I)=OROUND(Rdgs(I),4)
210 NEXT I
220 END
High-Speed Transfer
from Memory
108 Chapter 4 Making Measurements
The following program transfers readings directly to the controller at the
fastest possible rate. This program configures the multimeter to take readings
at its maximum rate of >100k readings per second. Readings are output using
the SINT format. If the bus/controller cannot transfer readings at >200k bytes
per second, the reading rate will be slower.This is because, in the
high-speed mode, the multimeter waits until each reading is removed from
its output buffer before placing the next reading in the output buffer. In the
following program, the SYN trigger arm event is used to trigger the readings
(TRIG SYN could also be used). The SYN event is very important for
high-speed operation since it ensures the controller will be ready to accept
the first reading output by the multimeter. The TRANSFER statement (line
120) satisfies the SYN event and is the fastest way to transfer readings across
the GPIB, especially when used with the direct memory access (DMA) GPIB
interface.
Configuring the reading memory format (MFORMAT command) to match
the output format (OFORMAT command) helps to ensure command) to
match the fastest transfer of readings from reading memory to the controller.
This is because no conversion is necessary when the readings are recalled
from memory. For high-speed, low resolution readings (3.5 or 4.5 digits)
made on a fixed range, use the SINT format. (Because the SINT format uses
only 2 bytes per reading, multiple readings can be stored in memory and
transferred across the bus faster using the SINT output format than any other
format.) For the fastest transfer of high resolution readings (5.5 digits or
greater) made on a fixed range, use the DINT format. Whenever autorange
is enabled and transfer speed is critical, use the SREAL format (for readings
of 6.5 digits or less) or the DREAL format (for readings of 7.5 or 8.5 digits).
Disabling the display and any math operations will also ensure the fastest
transfer from reading memory to the controller.
!COMPUTER ARRAY NUMBERING STARTS AT 1
!DECLARE VARIABLE
!CREATE INTEGER ARRAY FOR BUFFER
!CREATE REAL ARRAY
!NUMBER OF READINGS = 30000
!ASSIGN MULTIMETER ADDRESS
!ASSIGN BUFFER I/O PATH NAME
!TARM SYN,TRIG AUTO, DCV 10V
!1.4µs INTEGRATION TIME
!SINT OUTPUT FORMAT
!30000 READINGS/TRIGGER, AUTO
!SAMPLE EVENT (DEFAULT VALUE)
!SYN EVENT, TRANSFER READINGS INTO
!QUERY SCALE FACTOR FOR SINT FORMAT
!ENTER SCALE FACTOR
!CONVERT EACH INTEGER READING TO REAL
!USE ABSOLUTE VALUE TO CHECK FOR OVLD
!IF OVLD, PRINT OVERLOAD MESSAGE
!MULTIPLY READING TIMES SCALE FACTOR
!ROUND TO 4 DIGITS