Description
What it does
The FB4-DMX WPISO takes a DMX512-A line and hands your controller the bit stream as a plain 3.3 V CMOS UART signal. Everything on the DMX side — transceiver, transient protection and cable common — is galvanically separated from your host ground, so the module breaks the ground loops that corrupt data and kill transceivers on long DMX runs.
The isolated side is powered by an on-board converter. You feed the module one 3.3 V rail and nothing else: no second supply, no external isolated DC/DC.
Why it is different
- Receive-only by hardware. The driver is permanently disabled at the silicon, so the module physically cannot talk back onto the line and corrupt a universe shared with other devices.
- Protection that is actually specified. On-board TVS and series protection on the pair, qualified to IEC 61000-4-2, -4-4 and -4-5; ±15 kV ESD-rated transceiver; 1/8 unit load, so up to 256 modules can share one line.
- Defined behaviour when the bus is dead. Fail-safe biasing holds the output in the idle (MARK) state for an open, shorted or unterminated bus — no random data when a cable is pulled.
- Two status LEDs show host power and isolated-side power separately, so a dead isolated rail is visible without a meter.
- I²C control interface with an open-drain interrupt on the same connector, including a hard-wired module-present bit your firmware can read back.
Specifications
| Supply | 3.0–3.6 V single rail, 5 mA typical |
|---|---|
| Host interface | UART data out + I²C control, 7-pin ZH 1.5 mm connector |
| DMX interface | DMX512-A / RS-485 receive, 250 kbit/s, 1/8 unit load, 3-pin XH 2.5 mm connector |
| Isolation | Functional; barrier type-tested to 3.75 kVrms / 3 kVrms (1 min). Both sides must be SELV — this is not a mains safety barrier. |
| Common-mode transient immunity | 100 kV/µs across the barrier |
| Board size | 46.0 × 24.0 mm, 2 × ø3.5 mm mounting holes on 38 mm centres |
| Operating temperature | −25 °C to +85 °C |
In the box
16 assembled and tested modules. Mating harnesses are not included: J2 mates with a ZHR-7 housing (JST ZH, 1.5 mm) and J1 with an XH-3Y housing (JST XH, 2.5 mm), or equivalents.
No 120 Ω terminator is fitted. If a module sits at the end of a DMX line, fit 120 Ω across the two data pins in your harness.
