Closes every hardware question that was blocking the integration design,
so the design now rests on measurements rather than assumptions.
Probe results, all against the real printer:
- GS I 1 returns 0x20, unique against 0x01/0x0D/0x13. This is what keeps
the integration small: model identity stays a byte and the existing
per-job identification flow works. Had it returned nothing or 0x01 the
POS895 would have been indistinguishable from a TM-T30III by probe, and
model identity would have had to come from discovery instead.
- GS I 66 and 67 are blank, so the model-name fallback the work items
proposed is useless here. GS I 68 returns the serial, and it matches
the SPRT discovery serial exactly, which makes it a correlation key
between a discovered printer and a connected one.
- GS ( L prints nothing. ESC * 33 and GS v 0 both render correctly across
the full 576 dots, so the adapter uses PrintImageBitModeAsync and the
GS v 0 work item is dropped as redundant.
- ESC t is honoured and index 18 really is CP852; 2 and 0 also render.
That last one exposed a fleet-wide bug that is deliberately left out of
scope: PrintTextAsync hardcodes CP852 for every printer, and CP852 cannot
encode e-grave, a-grave, u-grave, e-circumflex, i-grave or o-grave, so
French and Italian accents are dropped on the Epsons too. Now known to be
fixable via ESC t 2, but it needs its own spec.
The design spec covers discovery composition, the adapter, the three
switch registrations, testing and risks. It calls out that the
ReceiptConverterFactory WorkareaTicket switch defaults to 33 columns, so
missing it yields a POS895 printing kitchen tickets at the narrow
TM-U220 layout: wrong, but not obviously broken.
Claude-Session: https://claude.ai/code/session_01E6N3P4nSZLtp4BC2LXVref
The POS895 does not answer Epson's ENPC broadcast, so PrintServer never
registers it and every job for it fails with "Printer not found". The
feasibility notes listed the vendor's own discovery protocol as unknown
and expected a packet capture to recover it, which is what this does.
Captured pktmon traffic while running the vendor EasySet tool on the
printer's segment. The protocol is:
query UDP broadcast 255.255.255.255:3289, sent FROM source port 9100
53 50 52 54 2D 49 6E 66 6F 72 00 00 0D "SPRT-Infor" 00 00 0D
reply from <printer>:3289 back to <querier>:9100, 39 ASCII bytes
"28-0e-8b-3d-ca-f1 2608120478"
MAC, 17 chars 12 spaces serial, 10 chars
The printer's address is the reply's source IP. Pos895Test now sends this
probe and parses the replies; run against the real printer it returns the
same MAC and serial the vendor tool got, so the reimplementation matches.
Two useful side effects. Port 3289 is the same UDP port ENPC uses, so a
composite IDiscoveryService can share one socket. And the querying machine
and the printer sat in different /24s of one flat segment, so the /24 TCP
sweep the notes originally preferred would have missed this printer.
The print test is commented out at the bottom of Program.cs rather than
deleted; it confirmed Font A is 48 columns and that GS ! magnification
works at width 1x/2x/3x with height 2x.
Notes updated: the discovery work item is no longer the largest one, the
compatibility table records DLE EOT and GS ! as confirmed and ESC d as
apparently ignored, and the answered questions are separated from the
ones still open.
Claude-Session: https://claude.ai/code/session_01E6N3P4nSZLtp4BC2LXVref
Study-only writeup of what supporting the SPRT-derived POS895/POS896
ESC/POS clones would take: no vendor SDK linking, a 576-dot IPrinter
adapter, non-ENPC discovery, a sturdier printer-ID probe, and the
hardware checks still open.
Claude-Session: https://claude.ai/code/session_01WAG8xogHxq9hDJScu386Jf
