Distributed Remote I/O | Products — SGT Systems Limited

Overview

Distributed Remote I/O moves the I/O modules out of the central control cabinet and onto the machine itself — close to the sensors and actuators they serve. Instead of pulling 200 individual conductors back to a single PLC rack, each junction box terminates the local field wiring and sends a single Ethernet cable back over Profinet, EtherNet/IP, EtherCAT, or Modbus TCP.

Engineered for plants where cabling, junction-box space, and commissioning hours are the real cost drivers. A typical bottling line replaces 12 racks × 200 wires with 12 nodes × 1 patch cord — saving kilometres of cable, hundreds of hours of pulling, and dramatically faster fault isolation.

DIN-rail field modules — IP20 for cabinet, IP65/IP67 for direct machine mount
DI / DO / AI / AO / RTD / TC — pluggable, mix-and-match, hot-swap on most heads
Profinet, EtherNet/IP, EtherCAT, Modbus TCP — speak the bus your PLC already runs
MRP ring redundancy — < 200 ms heal time on a broken cable

How It Works

A bus coupler (head module) sits at the left of each rail and handles fieldbus communication. Behind it, you snap in any combination of I/O modules; the backplane bus auto-detects them and the master pulls a process image every cycle. Configuration is done once in the engineering tool; from then on the master treats the remote node identically to a local rack.

Field wiring — sensors and actuators terminate directly at the node, 1–3 m runs
Coupler scan — reads/writes the backplane I/O at sub-millisecond intervals
Fieldbus packet — coupler exchanges the process image with the PLC over Profinet/EIP/EtherCAT
PLC main scan — reads the remote node as part of its normal I/O image
Diagnostics back — channel-level fault codes, short-circuit, wire-break

Features

Channel-level diagnostics — per-channel short / open / overload reported back to the PLC
Hot-swap modules — pull a faulty module without de-energising the rail
Configurable I/O density — 4, 8, 16, 32 channels per module to match the machine
HART pass-through — on analog modules, full HART diagnostics for smart instruments
MRP ring — redundant ring topology, < 200 ms heal, no single point of failure
Galvanic isolation — 500 VAC channel-to-channel and channel-to-bus on critical modules
IP65/IP67 variant — mount directly on the machine, no cabinet required
FDI / GSDML — standard device descriptions for any major engineering tool

Use Cases

Long conveyor systems — one node every 20 m instead of hundreds of metres of multicore
Modular machinery — each station carries its own I/O node, plug-and-play to the master
Process skids — one node per skid, single Ethernet cable to the main DCS
Water / wastewater plants — IP67 nodes at distant pumps, no cabinet needed
Wind & solar farms — per-string monitoring with daisy-chained fieldbus
Retrofit projects — add I/O to existing PLCs without rewiring the marshalling cabinet

Specifications

Couplers: Profinet, EtherNet/IP, EtherCAT, Modbus TCP, CC-Link IE; dual RJ-45 for ring
Digital modules: 4 / 8 / 16 / 32 channel DI & DO; 24 VDC source/sink; 0.5 A per ch
Analog modules: 4 / 8 ch 0–10 V, ±10 V, 0/4–20 mA, 16-bit; HART option
Temp modules: 4 / 8 ch RTD (PT100/1000), TC (J/K/T/N/R/S/B), 16-bit, cold-junction comp
Cycle time: < 1 ms backplane, 4 ms fieldbus typical, < 250 µs EtherCAT
Power: 24 VDC, redundant supply option, 50–500 mA per module
Environment: IP20 cabinet or IP65/IP67 field; −25 to +60 °C; 5 g vibration
Certifications: CE, UL 508, ATEX Zone 2 / Class I Div 2 variants, DNV-GL marine