HP E1429A manual FETChchan Subsystem Command Reference

∙The data may be read any number of times, as long as no parameters have changed which could affect new data (such as changing TRIGger:STARt:COUNt, ARM:STARt:COUNt, SENSe:SWEep:OFFSet:POINts, *RST, *RCL, etc.). If any measurement parameters are changed, then error -230;"Data corrupt or stale" will occur.

∙The number of readings that FETCh? is going to return for each channel can be determined two ways. The simplest way is to use the FETCh:COUNt? query. This will return how many readings will be fetched. The second way is to calculate how many readings should have been taken. This number is calculated as:

(number of start triggers) * (pre-arm readings + post-arm readings) The above equation may be built from the following queries:

(ARM:STARt:COUNt?) * (TRIG:STARt:COUNt?)

The number of pre-arm readings may be determined by taking the absolute value of the query SENSe:SWEep:OFFSet:POINts? which returns either 0 (no pre-arm readings), or a negative number which is the pre-arm count.

If the measurement was ABORted, then FETCh:COUNt? is the only reliable way to determine how many readings will be returned by the FETCh<chan >?

∙As noted immediately above, it is possible to calculate the end of pre-arm data and the beginning of post-arm data when both are present in a measurement. The data will always be returned with the specified number of pre-arm readings followed by post-arm readings.

∙If the measurement was aborted and pre-arm readings were specified, there is no way to determine how many readings (if any) are post-arm. The HP E1429 will attempt to bring back TRIGger:STARt:COUNt number of readings and if there are not that many, it will bring back as many readings as were taken.

∙Related Commands: ABORt, FORMat:DATA, INITiate:IMMediate, READ?, ARM:STARt:COUNt, TRIGger:STARt:COUNt, SENSe:SWEep:OFFSet:POINts, STATus subsystem

∙*RST Condition: none

Example 1 Obtaining readings from the HP E1429

CONF1:ARR:VOLT (30),.6,(@1)	Configure for 30 readings on channel 1,
	port 1
INIT	Take the measurement
FETC?	Get readings from channel 1.

FETCh[<chan>] Subsystem Command Reference 225