Just to follow-up to my previousrequest, and perhaps to save
someone else some time, these are the answers to my questions:
I managed to find Epson TM series printer technical manuals on
the following website: http://www.epsonexpert.com
(registration is required). The technical manual specifically
details DIP switch settings.
As for the Micros IDN printer loopback test connector, I was
unable to find a documented source. However, on the assumption
that the IDN interface is a balanced RS-422 serial connection,
I was able to cobble together a connector that works. Using an
RJ25 (6P6C) connector, wire pin 2 to pin 4, and pin 3 to pin 5;
pin 7 is probably ground, and is unnecessary for this purpose.
NB: pin 1 is the leftmost pin when RJ25 is held with cable-side
toward you, and locking clip facing down. I am assuming that the
self-test is sufficiently rigorous so that this experimentally derived
connector isn't triggering a false positive.
To use this connector, use the following procedure:
(1) Turn OFF the Epson TM-T88 printer,
(2) On the IDN interface in back, turn ON dip switch #7,
(3) Plug loopback test connector into either IDN port,
(4) Ensure printer has paper,
(5) Turn ON printer.
The resulting print-out will give the results of the test.
Hope this helps someone.