Description

1. What the suffix means SJ-D-PT = transmitter, 5 V TTL in, differential 2 V pp out, 125 kbit/s, –25 °C to +70 °C
   SJ-D-PR = receiver, differential 200 mV minimum in, 5 V TTL out, same temp range
   Both share 24 VDC ±10 % supply, 30 mA typical, 2 kV isolation, 15 mm DIN-rail footprint, IP20.
2. Safety first—lock-out & verify Transceivers sit on the 24 VDC logic rail but share the same cabinet as 110 VDC brake contacts.
   Lock the controller breaker, hang a lock-out tag and wait 60 s for the rail to fall below 5 V.
   Keep the new Nanjing Zhuye transceiver pair in its anti-static bag until mounting—CMOS opto-couplers can latch at 15 V static.
3. Mechanical mounting—keep the noise out Snap the modules onto 35 mm DIN rail inside the controller.
   Maintain 50 mm clearance above and below; every 10 °C rise halves opto-isolator life.
   If the cabinet is < 100 mm deep, mount vertically with terminals down—this allows convection chimney and keeps induced 50 Hz fields away from the twisted pair.
   Nanjing Zhuye supplies a free DIN clip (NY-DIN-SJ) for panel-mount when rail space is tight.
4. Wiring map (print and stick inside door) 24 V & 0 V – 1.5 mm², 105 °C silicone, torque 0.5 N·m
   TTL IN (PT) – 0.2 mm², 30 cm max to MPU UART pin
   TTL OUT (PR) – 0.2 mm², 30 cm max to MPU RX pin
   A/B (twisted pair) – 0.5 mm², 600 V, 120 Ω characteristic impedance, twist 9–12 turns/metre
   Shield – foil + drain, grounded at ONE end only (usually the group cabinet)
   Termination: 120 Ω ±5 %, 0.25 W, carbon film, at extreme ends of the bus (DIP-1 ON on last device)
5. Baud-rate & distance cheat-sheet 125 kbit/s (standard Otis group) – max 1.2 km, 32 nodes, termination both ends
   38.4 kbit/s (older HCA) – max 1.8 km, 64 nodes, same termination
   187.5 kbit/s (Gen2 high-speed) – max 500 m, 128 nodes, use SJ-D-PT/PR-F fibre version (supplied by Nanjing Zhuye)
6. Power-up & functional test Apply 24 VDC; green “PWR” LED steady on both PT and PR.
   Transmit test: short TTL IN to +5 V for 100 ms; differential A-B voltage should read 2.0 V pp on scope, rise time < 50 ns.
   Receive test: inject 200 mV pp 125 kHz square wave across A-B; TTL OUT must toggle 0–5 V with < 100 ns delay.
   If differential voltage < 1.5 V, termination is missing or cable is shorted.
7. Temperature & lifetime model Opto-isolators: 50 kh @ 70 °C, double every 10 °C drop.
   TVS diode (SMAJ33A): 1 kW peak, 40 kh @ 45 °C.
   Electrolytic C1 (10 µF, 35 V): 2 000 h @ 105 °C, 64 kh @ 45 °C.
   Translate to building traffic: Light traffic (office, 8 h/day, 5 days/week) – optos ≈ 30 years, full board ≈ 20 years; inspect every 5 years. Medium traffic (mall, 12 h/day, 7 days/week) – optos ≈ 12 years, full board ≈ 10 years; inspect every 2 years. Heavy traffic (metro, 20 h/day) – optos ≈ 6 years, full board ≈ 5 years; inspect every 12 months.
8. Preventive inspection checklist Monthly: visual LED, listen for crackling (arcing termination). Quarterly: scope A-B differential; > 5 V overshoot indicates missing resistor. Annually: megger A-B to PE > 100 MΩ; < 10 MΩ indicates moisture ingress. Bi-annually: torque test 24 V screws; vibration loosens them, causing E-COM faults.
9. Rapid swap (downtime < 3 min) a) Power down, lock-out, wait 60 s. b) Photograph A-B and TTL orientation with phone. c) Remove DIN clip, slide old modules out. d) Insert new Nanjing Zhuye SJ-D-PT/PR, snap onto rail. e) Restore 24 V, A-B, TTL, set DIP switches as photo. f) Power up, verify green LED on both units. g) Run group test—every car must answer every call. h) Log serial number and date; return old units for recycling.
10. Recycling & sustainability Nanjing Zhuye offers prepaid DHL labels inside every carton.
    Returned modules are stripped: gold fingers go to certified refinery, plastic housing re-granulated, copper inductors remelted.
    One recycled transceiver pair saves 0.8 kg CO₂—enough to power the same controller for a week.