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Description
Application Scenarios
A food-and-beverage packaging plant in the Midwest was running a mix of legacy equipment: a PLC-5 supervisory controller managed the main production line, while several standalone SLC 500 controllers operated individual packaging machines. The machines were essentially “islands” — the PLC-5 could not see their I/O, so operators had to walk the floor to check status, and there was no way to coordinate line-wide start/stop or collect production data centrally.The plant’s controls engineer installed a 1747-DCM in each SLC 500 rack and connected them to the existing RIO link via Belden 9463 cable in a daisy-chain configuration. Each 1747-DCM was configured with DIP switches to set its logical chassis address and I/O group, and the PLC-5’s RIO scanner was programmed to recognize the SLC controllers as remote I/O racks. Suddenly the packaging machines were visible to the supervisory controller: the PLC-5 could read machine status, write control commands, and coordinate line-wide sequences — all without replacing a single SLC 500 controller. The 10,000 ft cable reach at 57.6K baud meant the modules could sit at opposite ends of the 400,000 sq ft facility without signal repeaters. Best of all, the entire integration took one weekend, and the plant extended the service life of its installed SLC 500 fleet instead of funding a full control-system replacement.
Parameter
| Main Parameters | Value / Description |
|---|---|
| Product Model | 1747-DCM |
| Manufacturer | Allen-Bradley / Rockwell Automation (USA) |
| Product Category | Direct Communication Module (DCM) — RIO adapter, no local logic execution |
| Series / Platform | SLC 500 (Bulletin 1747) |
| Lifecycle Status | Discontinued (End-of-Life / Legacy) — new surplus, tested-pull, and refurbished units remain available; 12-month warranty is standard from reputable suppliers |
| Slot Occupancy | Single slot in any SLC 500 chassis (fixed or modular) |
| Backplane Current | 360 mA @ 5 VDC; 0 mA @ 24 VDC — total power dissipation 1.80 W |
| Communication Protocol | Allen-Bradley Remote I/O (RIO) |
| Network Role | RIO adapter (appears as a remote I/O rack to the scanner) |
| Compatible Scanners | PLC processor with integral RIO scanner; 1771-SN RIO scanner; 1747-SN RIO scanner — compatible with all RIO scanners |
| Cable Type | Belden 9463 (shielded twisted-pair), daisy-chain topology; 6-pin Phoenix connector |
| Data Rates / Cable Distance | 57.6K baud → 3,048 m (10,000 ft); 115.2K baud → 1,524 m (5,000 ft); 230.4K baud → 762 m (2,500 ft) |
| Terminating Resistor | 82Ω (½ W) for extended node; 150Ω for standard node — installed at first and last node |
| Extended Node Capability | Up to 32 adapters on the RIO link (with 82Ω termination) |
| Chassis Addressing | ¼, ½, ¾, or full logical chassis (configured via SW2-5 / SW2-6) |
| RIO Words Transferred | ¼ = 2 words (1 RIO + 1 status); ½ = 4 words (3 RIO + 1 status); ¾ = 6 words (5 RIO + 1 status); full = 8 words (7 RIO + 1 status) |
| Starting I/O Group | 0, 2, 4, or 6 (configured via SW1-7 / SW1-8) |
| Rack Address | 1–77 octal (configured via SW1-1 through SW1-6) |
| Clear on Fault | Configurable via SW2-3: hold last state, or clear data on communication failure |
| Last Rack | Configurable via SW2-4 — defines whether this is the final adapter on the link |
| Configuration Method | Two 8-bit DIP switch banks (SW1, SW2) — no user programming or software required |
| Status Indication | FAULT LED (red): internal fault (steady) or configuration error (flashing); COMM LED (green): normal (steady), scanner in program/test/fault mode (flashing), communication failure (off) |
| No Local Push-Buttons / Display | None — all configuration via DIP switches; all diagnostics via the two LEDs |
| Operating Temperature | 0°C to 60°C (32°F to 140°F) — most sources; Rockwell SLC 500 family spec 0°C to 55°C (131°F) |
| Storage Temperature | -40°C to +85°C (-40°F to +185°F) |
| Humidity | 5% to 95% RH, non-condensing |
| Vibration | 2.5g @ 5–2000 Hz |
| Operating Shock | 30g |
| Dimensions | 144.5 × 34.6 × 130.18 mm (5.72 × 1.37 × 5.15 in) per most technical sources; alternate listing 152 × 51 × 152 mm |
| Weight | 0.20–0.45 kg (0.37–1.00 lb) depending on source; common value 0.25 kg (0.55 lb) |
| Protection Rating | IP20 (chassis installation) |
| Certifications | UL, CSA, CE, ATEX, IECEx, Korean KC, RCM; NEMA ICS 2-230, EN 50081-2 Class A, IEC 1000-4-2, IEC 1000-4-3 |
| Country of Origin | USA |
