Fluke PM-3390B, PM-3380B How to acquire a single shot trace, Preparations, This string data

GETTING STARTED WITH SCPI PROGRAMMING 2 - 7

2.4.1How to acquire a single shot trace

In the program example, a single shot trace acquisition of 8192 8-bit samples is done with a probe connected to input channel 1. The trace sample bytes are read from the GPIB as string characters. The number of response bytes and the number of samples are printed.

The TRIGger:SOURce command is used to specify input channel 1 as a trigger source. The TRIGger:LEVel command is used to reset the trigger level to e.g., 0.1 volts.

PREPARATIONS:

•Connect a probe to channel 1. After start up of the program you will be asked to trigger the acquisition with the open end of the probe, i.e., touch the probe or strike the probe on the table.

PROGRAM EXAMPLE:

’*****

’Acquire a single shot trace:

’*****
DIM tracebuf AS STRING * 16500	’Formats 8-bits sample
CALL Send(0, 8, "FORMat INTeger,8", 1)
CALL Send(0, 8, "TRACe:POINts CH1,8192", 1)	’Formats 8192 sample points

CALL Send(0, 8, "TRIGger:SOURce INTernal1", 1) ’Trigger-source = channel 1

CALL	Send(0,	8,	"TRIGger:LEVel 0.1", 1)	’Trigger-level = 0.1
CALL	Send(0,	8,	"INITiate", 1)	’Single shot initiation

PRINT "Trigger the CombiScope instrument by touching the probe tip."

PRINT ">>> Press any key when finished."
WHILE INKEY$ = "": WEND
CALL Send(0, 8,	"*WAI",	1)		’Waits for previous commands
				to finish
CALL Send(0, 8,	"TRACe?	CH1",	1)	’Queries for channel 1 trace
CALL Receive(0,	8, tracebuf$,		256)	’Reads channel 1 trace
’
’The contents of the tracebuf$ string is as follows:

’# 4 8194 <8> <byte 1> ... <byte 8192> <sum> <10>

’

nr.of.digits = VAL(MID$(tracebuf$, 2, 1))

nr.of.bytes = VAL(MID$(tracebuf$, 3, nr.of.digits)) - 2 sample.length = ASC(MID$(tracebuf$, 3 + nr.of.digits, 1)) / 8 nr.of.samples = nr.of.bytes / sample.length

PRINT	"Number	of	bytes	received ="; IBCNT%	’IBCNT% = number of bytes
PRINT	"Number	of	trace	samples ="; nr.of.samples

Note: Refer to section 3.4.3 "Conversion of trace data" about how to convert

this string data.