R?
R?
Syntax
R? [<max_count>]
Description
This query reads and erases readings from volatile memory up to the specified <max_count>. The readings are erased from memory starting with the oldest reading first. The purpose of this command is to allow you to periodically remove readings from memory that would normally cause reading memory to overflow (for example, during a scan with an infinite scan count).
Parameters
Name Type Range of Values Default Value <max_count> Numeric Maximum number of readings to be read and erased from memory, from 1 to 50,000. Erase all stored readings, up to 50,000
Remarks
-
This command is a special version of the DATA:REMove? command with faster execution time. You can read memory at any time using the R? command, even during a scan.
-
Readings can be acquired during a scan using the multiplexer and digital modules. For scanning measurements using the multiplexer modules, an error is generated if the internal DMM is disabled (see INSTrument:DMM command) or not installed in the mainframe. The internal DMM is not required for operations on the digital modules.
-
You can store up to 50,000 readings in memory and all readings are automatically time stamped. If memory overflows, the new readings will overwrite the first (oldest) readings stored; the most recent readings are always preserved. In addition, bit 9 is set in the Questionable Data Register's condition register (see Status System Introduction).
-
Each reading is returned with some combination of measurement units, time stamp, channel number, and alarm status information, depending on the settings set by the FORMat:READing commands. The time stamp is either in relative format (time in seconds since the beginning of the scan) or absolute format (time of day with date, based on the instrument's clock as set by the SYSTem:DATE and SYSTem:TIME commands). The choice of absolute and relative time is determined by the FORMat:READing:TIME:TYPE command.
-
The instrument clears all readings from memory when a new scan is initiated, when any measurement parameters are changed (CONFigure and SENSe commands), and when the triggering configuration is changed (TRIGger commands).
-
The instrument clears all readings from memory after a Factory Reset (*RST command) or after an Instrument Preset (SYSTem:PRESet command).
Return Format
The query returns a series of readings in Definite-Length Block format. The syntax is a pound sign (#) followed by a non-zero digit representing the number of digits in the decimal integer to follow. This digit is followed by a decimal integer indicating the number of 8-bit data bytes to follow. This is followed by a block of data containing the specified number of bytes.
For example:
Example
This query reads the two oldest readings and erases them from memory.
R? 2
Typical Response: #231+2.87536000E-04,+3.18131400E-03
See Also