How many switches per Cat5 β€” conductor budget + how to scale (3 direct / 8 via module)

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switches_per_cat5 2014 RAM 1500 Carputer β€” HOW MANY LIT SWITCHES PER Cat5 (and how to scale) Each lit switch needs only 2 of its OWN conductors:  contact β†’ a DI,  indicator LED β†’ a DO.   All switches SHARE one +12V + one GND conductor. BUDGET (direct):  8 conductors βˆ’ 2 shared rails = 6 left Γ· 2 per switch = 3 LIT SWITCHES PER Cat5. SCALE:  add a Cat5 per +3 switches  β€”ORβ€”  put a Modbus IO 8CH at the panel: switches wire LOCALLY, ONE Cat5 home-runs the BUS β†’ 8 switches per Cat5 (add modules to grow). LEGEND:  red = +12V  Β·  black = GND  Β·  blue = contactβ†’DI  Β·  green = indicatorβ†’DO  Β·  magenta = RS485 cluster_direct APPROACH A β€” DIRECT WIRING:  3 lit switches per Cat5 cluster_module APPROACH B β€” MODULE AT PANEL:  8 switches per ONE home-run Cat5 (the scalable way) sw1 SW1 (lit momentary) locator LED+ β†’ 12V locator LED- β†’ GND COM β†’ GND NO β†’ DI indicator β†’ DO cat5 ONE Cat5 = 8 conductors (std colors) W-Orange = +12V RAIL (shared by all 3) Orange = GND RAIL (shared by all 3) W-Green = SW1 NO β†’ DI1 Green = SW1 indicator β†’ DO1 W-Blue = SW2 NO β†’ DI2 Blue = SW2 indicator β†’ DO2 W-Brown = SW3 NO β†’ DI3 Brown = SW3 indicator β†’ DO3 sw1:no->cat5:wg sw2 SW2 (lit momentary) locator β†’ 12V/GND COM β†’ GND NO β†’ DI indicator β†’ DO sw2:no->cat5:wbl sw3 SW3 (lit momentary) locator β†’ 12V/GND COM β†’ GND NO β†’ DI indicator β†’ DO sw3:no->cat5:wbr cat5:g->sw1:ind cat5:bl->sw2:ind cat5:br->sw3:ind ctrl Waveshare ESP32-S3 8DI-8DO (MASTER) +12V GND DI1 DI2 DI3 (reads the 3 switches) DO1 DO2 DO3 (drives the 3 indicators) ctrl:v->cat5:wo +12V (1 conductor, shared) ctrl:g->cat5:o GND (1 conductor, shared) noteA RULE OF THUMB ────────────────── DIRECT:   3 lit switches per Cat5   (2 conductors each + shared 12V + shared GND) MODULE:   8 lit switches per home-run Cat5   (Cat5 carries the RS485 bus, not each switch) Every conductor here is mA-level signal/LED -> 24 AWG Cat5 is plenty. The only thick wire is the LOAD each switch turns on (relay -> light), nowhere near the Cat5. Stranded Cat5e + ferrules into the screw terminals. swA 8x lit switches wire LOCALLY to the module (short jumpers, not the home run) mod Modbus IO 8CH @ PANEL (RS485 slave) 8 DI (switches) Β· 8 DO (indicators) +12V GND RS485 A RS485 B swA->mod local jumpers (short) home ONE home-run Cat5 pair1 = RS485 A/B (all 8 switches' data) pair2 = +12V + GND (module power) 2 spare pairs mod:a->home:a home:p->mod:v 12V+GND ctrlB Waveshare ESP32-S3 (RS485 MASTER) RS485 A RS485 B +12V GND home:a->ctrlB:a noteB SCALE BEYOND 8:  add another Modbus IO 8CH (different RS485 address) on the SAME bus -> +8 switches.  daisy-chain RS485 down the line; up to ~32 devices share the two A/B wires.  -> 16, 24, 32... switches still on basically ONE thin Cat5 bus. ctrlB:v->home:p

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