HP 82479A Owner's Manual page 53

Keywords
USE3421
IISE=421 [ device specifier | + 1]
device specifier — device specifier of the desired HP 3421 A instrument.
This statement is the same as IMI T=d 21 execpt that it does not reset the instrument to the power-on
state. Note that if the specified device is not an HP 3421 A, unpredicable results may occur.
WRITEBYTE
MEITEEREYTE slot numbers numeric expression
slot number - The number of a slot in the HP 3421A containing a digital card.
numeric expression - Value to be written to the output port.
This statement writes a decimal value to the output port of a digital I/O card.
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