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216 L4400 User’s Guide
8 L4450A 64-Bit Digital I/O with Memory and Counter
CONF:DIG:WIDT WORD, (@1101)
CALC:COMP:DATA #HF00F, (@1101)
CALC:COMP:TYPE EQUAL, (@1101)
SENS:DIG:INT:MODE COMP, (@1101)
SENS:DIG:INT:ENAB ON, (@1101)
CALC:COMP:STAT ON, (@1101)
Once the pattern matching state is turned on, the L4450A polls for the pattern
#HF00F to appear on the data lines of channel 101. The interrupt line will be
asserted when the pattern is matched. In the example above the last command,
CALCulate:COMPare:STATe, also sets the mainframe alarm on a pattern
match.
You can use pattern matching to start or stop a buffered (memory) input
transfer. When the desired pattern is found, the L4450A can be set to start or
stop a capture.
For example, the following commands establish a byte pattern match on
channels 101 and 201. When the pattern is found, 200 samples are captured.
CONF:DIG:WIDTH BYTE,(@1101,1201)
CALC:COMP:DATA:BYTE 140,(@1101,1201)
CALC:COMP:STAT ON,(@1101,1201)
DIG:MEM:SAMP:COUN 200,(@1101,1201)
DIG:MEM:COMP:ACT STAR,(@1101,1201)
DIG:MEM:ENAB ON,(@1101,1201)
Counter
The L4450A has two 10 MHz frequency counter/totalizer measurement input
channels. The counters can operate in two general modes: Totalizer mode, and
Initiated Measurement mode. In the totalizer mode, the counter acts as a basic
totalizer. In the initiated measurement mode, the counter can make frequency,
period, duty cycle, and pulse width measurements.
Tot al iz er Mo de
Totalizer mode is the default operating mode for the counters. When the
counter is configured for TOTalizer mode, it automatically starts running.
The totalized count can be read, reset, scanned, and monitored.
The simplest way to take a totalizer measurement is to use the
MEASure form
of the command. For example, the following command configures the totalizer
on the first bank, initiates the measurement, and returns the result. The data
is returned in a floating point format.
MEAS:COUN:TOT? READ, (@1301)
You can also reset the totalizer count by setting the parameter to RRESet. For
example, the following command configures the totalizer on the first bank,
initiates the measurement, and returns the result. The totalize count is reset
when the data is read.