Honeywell HXMT9 / HXMT9X - Manual (Page 86)

Appendix B
Connector Pin Outs
The has a 50-pin connector used for alarm input and output,
RS-232 network connections, VCR trigger pulse, and updating the
multiplexer’s firmware. A sub-board is supplied to simplify connections.
See the illustration below for connection details.
multiplexer
< Figure 61 > Connector Sub-Board
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