Specifications
SAM RJ45 bus terminators, sold in pairs
Correct termination at each end of a transmission line stops signal reflections. Reflections corrupt data and cause unequal signal quality across nodes on a shared bus. SAM Controllers builds encapsulated RJ45 terminators with the pinout, circuit, and shielding your network requires.
Every order ships two terminators. A transmission line needs termination at both ends. The price you see covers the pair.
Why we build these
A terminator is a small part with a large failure mode. A missing terminator, a wrong resistor value, or a wrong pinout produces intermittent errors. The bus passes a bench test and then fails in the field. The fault looks like a software problem or a bad node. Crews replace working hardware before they check the termination.
Commodity terminators rarely state a tolerance, a pinout, or a test result. We build each unit to a stated configuration and we measure it. Every unit passes a test before shipment. You install a known value on known pins, and you remove termination from the list of suspects.
Pick the pinout your equipment uses
RJ45 serial pinouts differ by vendor. The two configurations below cover the common installed base. Check your device manual before you order.
| Pinout | Protocols and equipment |
|---|---|
| Pins 4 + 5 | Modbus RTU per the Modbus.org serial line specification; Schneider Electric Altivar, Zelio, and Modicon equipment |
| Pins 1 + 2 | CANopen (CiA 303-1); BACnet MS/TP controllers; DMX512-A (ANSI E1.27-2); Allen-Bradley PowerFlex drives |
Circuit options
Every circuit uses 1/4 W resistors. Each one is available with 1% or 0.5% tolerance. Pick the tolerance with the circuit in the option picker.
- Standard, 120 Ω — one precision resistor across the data pair. The correct choice for most CAN, Modbus RTU, RS-485, BACnet, and DMX networks.
- RC filter, 120 Ω + 1 nF — a series capacitor blocks DC current. Idle power draw drops to near zero. The circuit matches the Schneider VW3A8306RC footprint. Use it on battery-powered and solar-powered nodes.
- CAN FD split, 2 × 60 Ω + 4.7 nF — the split network shunts common-mode noise to ground. Use it for CAN FD above 2 Mbps and for EMC-critical test setups.
- Uncommon values, 100 Ω / 150 Ω / 220 Ω — for RS-422 over Cat5e, Modbus over 150 Ω cable, and Profibus-type networks. Commodity vendors do not stock these values. We build them on the same RJ45 bodies.
Body: shielding and potting
Shielding
Choose the shielded metal body where drives, inverters, or welders run near the bus. The metal shell carries coupled noise away from the data pair. Choose the unshielded body for indoor building networks in low-noise construction. For a floating shell or a capacitor-coupled shell, state the requirement in the quote form.
Potting
Potting fills the connector body with a resin. The resin holds the resistor and its solder joints against vibration. It also keeps moisture and dust off the circuit. All three materials give the same electrical result. They differ in hardness, in resistance to chemicals, and in whether a technician can open the body later.
| Potting | What it does | Pick it for |
|---|---|---|
| Soft silicone | Stays flexible after cure. The resin absorbs shock and moves with the parts through temperature swings. A technician can cut it out. | Bench work, indoor panels, and any build you may need to open. Lowest cost. |
| Hard silicone | Cures firm. It resists abrasion and vibration better than soft silicone. Removal is still possible with effort. | Mobile equipment and panels that vibrate. |
| Epoxy | Cures rigid and bonds to the connector body. It gives the best resistance to moisture, solvents, and vibration. Removal destroys the connector. | Outdoor cabinets, washdown areas, and chemical exposure. |
Custom and build-to-order
We build other connectors and circuits by quote:
- RJ11 / RJ12 (6P6C) terminators on pins 3 + 4
- DB9 and M12 connector bodies
- RS-485 fail-safe bias networks with pull-up and pull-down resistors
- Common-mode chokes and custom passive filters
- Other resistor values and tighter tolerances on request
- Volume pricing for 10-packs
Request a quote with your connector, pinout, values, and quantity.
Quality and origin
- Resistors: 1/4 W, with 1% or 0.5% tolerance.
- Testing: we test 100% of units before shipment.
- Protection: potted bodies protect internal components to IP30.
- Pins: gold-plated connector pins.
- Origin: assembled in Pittsboro, North Carolina, USA.