Chapter 4 Making Measurements 107
50 OUTPUT 722;"ACV 10" !AC VOLTS, 10V RANGE
60 OUTPUT 722;"NPLC 0.1"" !0.1 PLC INTEGRATION TIME
70 OUTPUT 722;"ACBAND 10E3,20E3" !SIGNAL BETWEEN 10kHz AND 20kHz
80 OUTPUT 722;"NRDGS 100, AUTO" !100 READINGS/TRIGGER, AUTO SAMPLE EVENT
90 OUTPUT 722;"TARM SGL" !TRIGGER READINGS
100 END
Fast ACI/ ACDCI Example The following program measures AC current at a fast rate. This program uses
the default delay time. You can achieve faster reading rates by specifying a
shorter delay time; the resulting settling time, however, may not produce
accurate measurements. You can also achieve unspecified faster reading rates
by specifying less integration time in line 50. This program can be adapted
to AC+DC current by using the ACDCI command instead of the ACI
command in line 40.
10 OUTPUT 722;"PRESET FAST" !TARM SYN, TRIG AUTO
20 OUTPUT 722;"MFORMAT SINT" !SINT MEMORY FORMAT
30 OUTPUT 722;"MEM FIFO" !ENABLE READING MEMORY, FIFO MODE
40 OUTPUT 722;"ACI 100E-3" !AC CURRENT, 100mV RANGE
50 OUTPUT 722;"NPLC 0.1" !0.1 PLC INTEGRATION TIME
60 OUTPUT 722;"ACBAND 10E3,20E3" !SIGNAL BETWEEN 10kHz AND 20kHz
70 OUTPUT 722;"NRDGS 100,AUTO" !100 READINGS/TRIGGER, AUTO SAMPLE EVENT
80 OUTPUT 722;"TARM SGL" !TRIGGER READINGS
90 END
Fast FREQ (or PER)
Example
The following program measures frequency at a fast rate. This program can
be adapted to measure period by using the PER command instead of the
FREQ command in line 40.
10 OUTPUT 722;"PRESET FAST" !TARM SYN, TRIG AUTO
20 OUTPUT 722;"MFORMAT SREAL" !SINGLE REAL MEMORY FORMAT
30 OUTPUT 722;"MEM FIFO" !ENABLE READING MEMORY, FIFO MODE
40 OUTPUT 722;"FREQ 10, .1" !FREQUENCY, 10V RANGE, 100µs GATE TIME
50 OUTPUT 722;"ACBAND 10E3,20E3" !SIGNAL BETWEEN 10kHz AND 20kHz
60 OUTPUT 722;"NRDGS 100, AUTO" !100 READINGS/TRIGGER, AUTO SAMPLE EVENT
70 OUTPUT 722;"TARM SGL" !TRIGGER READINGS
80 END
High-Speed Transfer
across GPIB
Configuring the output format (OFORMAT command) to match the format
used by the A/D converter (either SINT or DINT) ensures the fastest. transfer
of readings to the controller. This is because no format conversion is required
in the multimeter. For high-speed, low-resolution readings (3.5 or 4.5 digits)
made on a fixed range, use the SINT output format. (Because the SINT format
uses only 2 bytes per reading, multiple readings can be 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 output format.
The multimeter is capable of taking readings and outputting them to the
controller at >100k readings per second. Using the SINT output format at
this reading rate, the GPIB and controller must be able to transfer data at
>200k bytes per second. For Hewlett-Packard Series 200/300 Computers,
this requires a direct memory access (DMA) card. In addition, devices that
slow the operation of the GPIB bus and any unnecessary lengths of GPIB
cable must be removed to achieve maximum transfer rate.
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