R? [<max_readings>]

Reads and erases all measurements from reading memory up to the specified <max_readings>. The measurements are read and erased from the reading memory starting with the oldest measurement first.

Parameter	Typical Return
1 to 2,000,000 (readings) Default is all readings in memory.	(none)
Read and remove the three oldest readings: R? 3 Typical Response: #247-4.98748741E-01,-4.35163427E-01,-7.41859188E-01 The "#2" means that the next 2 digits indicate how many characters are in the returned memory string. These two digits are the "47" after the "#2". Therefore, the remainder of the string is 47 digits long: -4.98748741E-01,-4.35163427E-01,-7.41859188E-01

Parameter

Typical Return

1 to 2,000,000 (readings)

Default is all readings in memory.

(none)

Read and remove the three oldest readings:

R? 3

Typical Response: #247-4.98748741E-01,-4.35163427E-01,-7.41859188E-01

The "#2" means that the next 2 digits indicate how many characters are in the returned memory string. These two digits are the "47" after the "#2". Therefore, the remainder of the string is 47 digits long:

-4.98748741E-01,-4.35163427E-01,-7.41859188E-01

The R? and DATA:REMove? queries can be used during a long series of readings to periodically remove readings from memory that would normally cause the reading memory to overflow. R? does not wait for all readings to complete. It sends the readings that are complete at the time the instrument receives the command. Use Read? or Fetch? if you want the instrument to wait until all readings are complete before sending readings.
If you do not specify a value for <max_readings>, all measurements are read and erased.
No error is generated if the reading memory contains less readings than requested. In this case, all available readings in memory are read and deleted.
The number of readings returned may be less than that requested depending on the amount of reading memory in your instrument. You can store up to 1,000 measurements in the reading memory of the 34460A, 10,000 measurements on the 34461A, 50,000 measurements on the 34465A/70A (without the MEM option), or 2,000,000 measurements on the 34465A/70A (with the MEM option). If reading memory overflows, new measurements overwrite the oldest measurements stored; the most recent measurements are always preserved. No error is generated, but the Reading Mem Ovfl bit (bit 14) is set in the Questionable Data Register's condition register (see Status System Introduction).
The instrument clears all measurements from reading memory when the measurement configuration changes, or when any of these commands are executed: INITiate, MEASure:<function>?, READ?, *RST, SYSTem:PRESet.