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Allen-Bradley 1785-BCM PLC-5 Backup Communication Module – Technical Specifications and FAQ
Technical Specifications
| Parameter | Specification |
|---|---|
| Brand | Allen-Bradley |
| Manufacturer | Rockwell Automation |
| Model | 1785-BCM |
| Product Series | PLC-5 |
| Product Type | Backup Communication Module |
| Main Function | Provides backup communication and network switching between primary and secondary PLC-5 processors |
| Compatible Processors | PLC-5/15 Series B, PLC-5/20, PLC-5/25, PLC-5/30, PLC-5/40 and PLC-5/60 (Series B specification) |
| Installation | 1771 Local I/O Chassis |
| Mounting | Single-slot chassis installation |
| Communication Interfaces | 1 × High-Speed Serial Link (HSSL), 2 × DH+/Remote I/O |
| HSSL Communication Rate | 1.2 Mbaud (Series B) |
| HSSL Connection Distance | Up to 15 ft (approximately 4.57 m) |
| Data Buffer | 4K words |
| Backplane Current | 1.0 A at 5V DC |
| Customer Relay Rating | 0.25 A at 24V DC (resistive) |
| Wiring Arm | 1771-WG |
| Keying Locations | Between 8–10 and 34–36 |
| Operating Temperature | 0–60°C |
| Storage Temperature | -40–85°C |
| Relative Humidity | 5–95%, non-condensing |
| External Power Supply | Not required; powered through chassis backplane |
| Dimensions (H × W × D) | Approx. 150 × 35 × 260 mm (estimated module envelope; verify against actual revision) |
| Weight | Approx. 0.6 kg |
| Country of Origin | USA (distributor-listed; verify product nameplate) |
| Lifecycle Status | Discontinued / Legacy product |
FAQ
FAQ
Q1: What is the Allen-Bradley 1785-BCM?
A: It is a PLC-5 Backup Communication Module designed to provide communication backup and network switching between primary and secondary PLC-5 processors.
Q2: Which PLC-5 processors are compatible with the 1785-BCM?
A: The Series B specification lists compatibility with PLC-5/15 Series B, PLC-5/20, PLC-5/25, PLC-5/30, PLC-5/40 and PLC-5/60 processors. Compatibility depends on the module revision.
Q3: What communication interfaces does it provide?
A: It provides one High-Speed Serial Link (HSSL) interface and two DH+/Remote I/O communication interfaces.
Q4: What is the HSSL communication speed?
A: The Series B module communicates through HSSL at 1.2 Mbaud. It is used to exchange backup information between the primary and secondary PLC-5 systems.
Q5: Does the 1785-BCM require an external power supply?
A: No. It receives operating power through the 1771 I/O chassis backplane, requiring 1.0 A at 5V DC.
Q6: Which wiring arm is required?
A: It uses the Allen-Bradley 1771-WG wiring arm for field wiring connections.
Q7: What are the dimensions and weight?
A: The estimated module envelope is approximately 150 × 35 × 260 mm, and the approximate weight is 0.6 kg. Actual dimensions and weight may vary by revision and packaging.
Q8: Is the 1785-BCM discontinued?
A: Yes. The 1785-BCM belongs to the legacy PLC-5 product family and is discontinued by the manufacturer. It is generally available through surplus, refurbished, and industrial spare-parts suppliers.
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Packing & Delivery
We will use wear-resistant cartons to seal the boxes, and take photos for your confirmation before sealing. We will pack the boxes only after confirmation.
For express delivery, we will use DHL, UPS, TNT, FedEx and EMS.
Please rest assured that we have a deep cooperation with express delivery companies and can ensure that your goods are delivered to you in good condition.
