What Is the 1747-DCM/A Direct Communication Module?
How do you connect a supervisory PLC-5 processor to distributed SLC 500 controllers without scanning local I/O? The Allen-Bradley 1747-DCM/A answers that challenge. This Direct Communication Module (DCM) operates as an RIO adapter on a Remote I/O communication link. Consequently, it enables data exchange between a supervisory PLC and distributed SLC 500 processors. The module passes supervisory data to the distributed SLC processor. However, it does not scan the local I/O chassis itself. As part of the SLC 500 / Bulletin 1747 series, it occupies a single slot in a 1746 chassis. Configuration is handled via DIP switches, and multiple RIO baud rates are supported.
1747-DCM/A Technical Specifications
Every value below is verified against official Rockwell data. The module draws 360 mA at 5V DC from the backplane. It supports 57.6, 115.2, and 230.4 kbps RIO baud rates. Field wiring uses Belden 9463 cable and a 6-pin Phoenix connector. Up to 32 adapters can reside on the RIO link. The operating temperature range is 0 to 60 C.
- Backplane Current: 360 mA @ 5V DC
- RIO Baud Rates: 57.6 / 115.2 / 230.4 kbps
- Cable Type: Belden 9463
- Connector: 6-pin Phoenix
- Max Adapters: Up to 32
- Operating Temperature: 0 to 60 C
Installation and Configuration
The 1747-DCM/A is not hot-swappable. Therefore, never install, remove, or wire the module with power applied. Slot 0 is reserved for the processor or a 1747-ASB adapter. First, mount the module in a 1746 chassis. Next, set the DIP switches to define the RIO baud rate and adapter address. Then, connect the Belden 9463 cable to the 6-pin Phoenix connector. Finally, verify all wiring before applying power. Because the module does not scan local I/O, route field-side load power through an external supply as required by the family specifications.
Compatibility and Integration
The 1747-DCM/A integrates with SLC 500 systems and supervisory PLC-5 processors over Remote I/O. It acts as an RIO adapter, so it fits existing 1746 chassis backplanes. However, the SLC 500 / 1747 platform is discontinued. Rockwell recommends migrating to CompactLogix 5370/5380. Note that there is no direct SLC drop-in replacement; ControlNet or EtherNet adapters are available for modernization. For legacy support, the module remains compatible with existing RIO networks.
Maintenance and Lifecycle Status
Inspect the module periodically for secure connections and environmental compliance. Keep the operating temperature within 0 to 60 C and humidity within 5-95% non-condensing. Because the platform is discontinued, spare units may become scarce. Therefore, plan migration to CompactLogix to avoid downtime. For precise replacement guidance, contact AutoDCSTech with your exact requirements.
Availability & Condition at AutoDCSTech
| Part Number | 1747-DCM/A |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
