Time Interval and Frequency Counter

34 Programming CommandsOnce in binary dump mode the SR620 will takedata and send it to the controller as fast as it can.Binary dump mode is terminated when: the countexpires, the front panel reset key is pressed, orANY command is received. Because of the lastrestriction, the BDMP command should always bethe last command on a command line. The binarydata taken in this mode is NOT buffered. TheSR620 will take a data point, wait until thecontroller has read the entire point, take anotherpoint , etc.. Thus the maximum throughput maybe limited by the controller. It is recommended thatsome form of direct memory access transfer beused to maximize the transfer rate.The binary data is return as a 8 byte 2'scomplement binary integer. The least significantbyte is always sent first and an EOI is sent withthe most significant byte. To convert this numberto a number with the correct units the followingmust be done: 1) Convert the 2's complementnumber to signed integer form, and 2) multiply bya mode dependent scaling factor. The scalingfactors are given below.Examples of the binary dump mode are given inthe Programming Examples section of the manual.Scan Control CommandsANMD (?) jThe ANMD command sets the mode of the rearpanel DAC outputs. The parameter j =0 setsoutput #0 to produce a voltage proportional to themeasurement mean value, and DAC output #1 toproduce a voltage proportional to the jitter of themeasurement. The parameter j = 1 sets output 0to be a programmable voltage source and output 1to be proportional to the jitter. The parameter j = 2sets output 0 to be proportional to the mean andoutput 1 to be a programmable voltage source. If j= 3 both outputs are programmable sources.Binary Dump Scale FactorsDBEG (?) jThe DBEG command sets the start position of theinternal delay scan. The parameter j is the desireddelay in units of number of gate widths. Theallowable range is between 1 and 50000.DSEN (?) jThe DSEN command controls the enable status ofthe scanning delay. The parameter j = 0 sets thedelay OFF. If j =1 the delay is set to HOLD, that is, active but fixed in position. If j = 2 the delay isset to SCAN and will step by 1 step at the end ofeach group of samples. Note that the SR620MUST be in arming mode 6,7, or 8 for the delayscan to be functional and that an external trigger isrequired. (See the SCEN command.)DSTP (?) xThe DSTP command sets the size of the scanningdelay's step. The range of sizes that may be set isbetween 1us and 10ms in a 1,2,5 sequence. TheDSTP? query returns a floating point number with1 significant digit.HOLD (?) xThe HOLD command sets the hold time at eachscan point when in scan mode. The hold timemay range between 10ms and 1000s in 10msincrements. The HOLD? query return the holdtime as a floating point number.SCANThe SCAN command clears the current scan andstarts a new scan. The SCAN commandautomatically turns on the automeasure mode.This command should not be used if one wants tomanually control the acquisition of data during ascan. One should use the SCLR and STRTcommands instead.Time (2.712673611111111 E-12)/256 • 1.05963812934 E-14Width (2.712673611111111 E-12)/256 • 1.05963812934 E-14Rise/fall time (2.712673611111111 E-12)/256 • 1.05963812934 E-14Frequency (1.0 E 12)/(2.71267361111111 * 2^68) • 1.24900090270331 E-9 (x1000 OFF)Frequency (1.0 E 9)/(2.71267361111111 * 2^68) • 1.24900090270331 E-12 (x1000 ON)Period(2.712673611111111 E-12/256 •1.05963812934 E-14 (x1000 OFF)Period(2.712673611111111 E-15)/256 • 1.05963812934 E-17 (x1000 ON)Phase 360.000/2^32 • 8.3819032 E-8Count 1/256Ratio 1/2^40 • 9.094947017729282 E-13SR620 Universal Time Interval Counter