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READ[
<chan>
]
The READ? command is used to cause a measurement and to retrieve the readings
from that measurement. It is equivalent to executing the commands: ABORt,
INITiate:IMMediate, FETCh<chan >?.
Subsystem
Syntax
READ[
<chan >
]? [query only]
READ?
READ[<chan >]? returns readings from the specified channel in the format
specified by the FORMat:DATA command.
Parameters
Parameter
Name
Parameter
Type
Range of
Values
Default
Units
chan
numeric 1 | 2 none
Comments • READ? or READ1? will return data from channel 1 only. READ2? will return
data from channel 2 only.
• A READ1? followed by a READ2? will take two sets of measurements since an
INITiate is done with each read. If it is desired to look at each channel separately
for readings taken during the same time period, use the INITiate and FETCh?
sequence of commands instead of READ?.
• There are a few settings which, if allowed, would cause READ? to deadlock and
never complete. TRIGger:COUNt INFinite and ARM:COUNt INFinite are not
allowed because the measurement is continuous and therefore would never finish.
Also, ARM:SOURce BUS or HOLD and TRIG:SOURce BUS or HOLD are not
allowed because the parser would be unable to accept any commands to arm or
trigger the instrument during measurement because the READ? command would
not have completed. Any of the above settings active during a READ? command
will cause an error to occur and no measurements to be taken.
• The number of readings that READ? is going to return for each channel can be
calculated as
(number of start triggers) * (pre-arm readings + post-arm readings)
The above equation may be built from the following queries:
(ARM:COUNt?) * (TRIG:COUNt?)
READ[
<chan>
] Subsystem Command Reference 249