Multi-turn Absolute Encoder Reference Design
An illustrative field-level EtherCAT multi-turn absolute encoder design for servo axes, AGV steering wheels, robot joints and conveyor positioning: DC 24V supply, a single-turn magnetic encoder IC plus battery-free Wiegand multi-turn counting, dual EtherCAT ports (M12 D-coded, daisy-chainable), and an optional isolated RS-485 / SSI interface on the same platform. This page gives the function, selection notes and available VOOHU parts for 26 component positions.
Illustrative PCB ⇄ Schematic
The illustrative layout shows placement and component positions; click any position for selection notes, recommended parts and packages. The board is an illustration arranged by functional zone (not the actual layout): a real encoder uses a small round PCB, which is unfolded here by zone onto one drawing. The bus, RS-485 and power connectors sit on the bottom edge, and the shaft magnet is an external node.
The EtherCAT IN and OUT ports are identical; only 1 port and 1 differential pair are drawn (the other 10/100 pair is the same). The M12 D-coded sockets contain no magnetics, so the cable side first passes the VOOHU 10/100 LAN transformers T1 / T2 (WHS16037TG) for isolation and coupling; the PHY-side pairs are clamped by the ESD arrays D1 / D2 and go to the JL1111BI-NI (EtherCAT PHY), which connects to the slave controller ESC over MII; the ESC connects to the encoder MCU over PDI. Center-tap connection, termination and crystal load capacitor values per the PHY and transformer datasheets.
Board bill of materials
Click any row to jump to that position and view its selection notes
| No. | Zone | Position | Ref. | VOOHU category | Recommended part | Availability |
|---|---|---|---|---|---|---|
| 01 | A Dual EtherCAT ports | M12 D-coded bus socket ×2 (EtherCAT IN / OUT) | J1 J2 | — | — | Non-VOOHU |
| 02 | A Dual EtherCAT ports | 10/100 LAN transformer ×2 | T1 T2 | 10/100 LAN Transformers | WHS16037TG | VOOHU |
| 03 | A Dual EtherCAT ports | Ethernet ESD array ×2 | D1 D2 | TVS / ESD | WHALD03G4U | VOOHU |
| 04 | A Dual EtherCAT ports | EtherCAT 10/100 PHY ×2 | U1 U2 | Ethernet PHY | JL1111BI-NI | VOOHU |
| 05 | A Dual EtherCAT ports | PHY 25MHz crystal | Y1 | — | — | Non-VOOHU |
| 06 | B RS-485 / SSI (optional) | RS-485 / SSI interface terminal (optional) | J3 | — | — | Non-VOOHU |
| 07 | B RS-485 / SSI (optional) | Bus ESD (optional) | D3 | TVS / ESD | WHALD30E2B | VOOHU |
| 08 | B RS-485 / SSI (optional) | Bus signal-line CMC (optional) | L1 | Signal Line CMC | WHAC-3225B-510U0 | VOOHU |
| 09 | B RS-485 / SSI (optional) | Isolated RS-485 transceiver (optional) | U3 | — | — | Non-VOOHU |
| 10 | B RS-485 / SSI (optional) | Push-pull isolated power transformer (optional) | T3 | Push-Pull Transformers | WHST06K14A0 | VOOHU |
| 11 | B RS-485 / SSI (optional) | Push-pull driver + isolated-side LDO (optional) | U4 U5 | — | — | Non-VOOHU |
| 12 | C Sensing · Multi-turn | Single-turn magnetic encoder IC | U6 | — | — | Non-VOOHU |
| 13 | C Sensing · Multi-turn | Wiegand multi-turn sensor | U7 | — | — | Non-VOOHU |
| 14 | C Sensing · Multi-turn | Turn counter / non-volatile memory | U8 | — | — | Non-VOOHU |
| 15 | C Sensing · Multi-turn | Sensor supply filter molded inductor | L2 | Molded Inductors | WHYTP0320 Series | VOOHU |
| 16 | D Core | EtherCAT slave controller (ESC) | U9 | — | — | Non-VOOHU |
| 17 | D Core | Encoder MCU | U10 | — | — | Non-VOOHU |
| 18 | D Core | ESC configuration EEPROM | U11 | — | — | Non-VOOHU |
| 19 | D Core | MCU crystal | Y2 | — | — | Non-VOOHU |
| 20 | D Core | Core supply filter molded inductor ×2 | L3 L4 | Molded Inductors | WHYTA0420 Series | VOOHU |
| 21 | E Power | M12 A-coded power socket | J4 | — | — | Non-VOOHU |
| 22 | E Power | Reverse-polarity protection + input TVS | D4 D5 | — | — | Non-VOOHU |
| 23 | E Power | Power line common-mode choke (EMI) | L5 | Power Line CMC | WHAL-7060A-102T0 | VOOHU |
| 24 | E Power | Synchronous buck (24V→5V) | U12 | — | — | Non-VOOHU |
| 25 | E Power | DC-DC molded inductor | L6 | Molded Inductors | WHYT0630 Series | VOOHU |
| 26 | E Power | LDO ×2 (5V→3.3V sensor / digital) | U13 U14 | — | — | Non-VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 26 positions. Opens directly in Excel.
Datasheet collection
Datasheet PDFs for the VOOHU parts recommended on this board.
Design files & footprint library
Schematic, PCB, and VOOHU part footprints and 3D models.
Coming soonRequest the full encoder reference design packagefull package
Includes the BOM, datasheets for the recommended VOOHU parts and position-by-position selection notes. If you need selection advice for your bus protocol, connector style or isolation requirements, describe them in the request. We reply within 24 hours on working days.
