Agilent Technologies 1660A Series User Reference page 77

Connecting a Printer
GPIB Printers
Make sure the printer is in Listen Always (or Listen Only). For
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example, the figure below shows the GPIB configuration switches for
an GPIB ThinkJet printer. For the Listen Always mode, move the
second switch from the left to the "1" position.
Since the instrument doesn't respond to SRQ EN (Service Request Enable),
the position of the first switch doesn't matter.
Listen Always Switch Setting
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