Allen-Bradley 1785-BCM/C – Back-up Communications Module | PLC-5 Platform
Engineering Background
The Allen-Bradley 1785-BCM/C is a dedicated Back-up Communications Module engineered for the PLC-5 programmable controller family. Designed to maintain communication integrity in mission-critical industrial environments, this module provides redundant data-link capability, ensuring that control-system uptime is preserved even when primary communication paths are interrupted. It is a cornerstone component in high-availability PLC-5 architectures deployed across process industries, discrete manufacturing, and infrastructure automation.
Product Positioning
Targeted at procurement engineers and maintenance teams managing legacy PLC-5 installations, the 1785-BCM/C is the OEM-specified solution for communication redundancy. Konmask.com sources this module through verified industrial channels, offering authenticated units with full traceability — a critical requirement for regulated industries and safety-instrumented systems.
Complete Technical Specifications
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Part Number | 1785-BCM/C |
| Series / Revision | Series C |
| Module Type | Back-up Communications Module (BCM) |
| Compatible Platform | PLC-5 Programmable Controller Family |
| Communication Function | Redundant data-link backup for PLC-5 chassis |
| Backplane Interface | PLC-5 I/O chassis backplane |
| Form Factor | Single-slot PLC-5 module |
| Weight (approx.) | 560 g |
| Country of Origin | USA |
| Firmware / Revision | Series C (consult datasheet for firmware compatibility) |
| Operating Temperature | 0 °C to 60 °C (32 °F to 140 °F) |
| Storage Temperature | -40 °C to 85 °C |
| Relative Humidity | 5% to 95% non-condensing |
| Certifications | UL, CE (verify with current Rockwell documentation) |
Proven Application Environments
- Oil & Gas: Pipeline SCADA and compressor station control with redundant PLC-5 communication links
- Automotive Manufacturing: Transfer line and assembly automation requiring zero-downtime communication failover
- Water & Wastewater: Treatment plant control systems with high-availability requirements
- Power Generation: Turbine and boiler control panels using PLC-5 redundant architectures
- Chemical Processing: Batch and continuous process control with SIL-rated communication backup
- Mining & Minerals: Conveyor and crusher control systems in harsh environments
- Food & Beverage: CIP-compatible production lines with PLC-5 legacy infrastructure
Engineering Advantages
- Communication Redundancy: Provides seamless backup communication path, eliminating single points of failure in PLC-5 data-link architecture
- OEM Compatibility: Fully compatible with Allen-Bradley PLC-5 chassis and processor families without firmware modification
- Hot-Standby Capability: Supports hot-standby configurations to minimize switchover time during primary link failure
- Proven Field Reliability: Deployed in thousands of industrial installations globally with documented MTBF performance
- Series C Refinements: Incorporates hardware and firmware improvements over earlier series for enhanced signal integrity
- Minimal Footprint: Single-slot design preserves chassis space for I/O expansion
System Architecture & Signal Flow
The 1785-BCM/C installs in any available slot of a PLC-5 I/O chassis and interfaces directly with the PLC-5 processor via the chassis backplane. In normal operation, the primary communication channel handles all data-link traffic. Upon detection of a primary channel fault, the BCM module automatically assumes communication responsibility, maintaining data integrity between the PLC-5 processor and connected devices (HMI, remote I/O, DCS gateways). The switchover is transparent to the control program, requiring no ladder logic modification. Configuration is performed via RSLogix 5 or equivalent Allen-Bradley programming software.
Typical signal flow: PLC-5 Processor → Backplane → 1785-BCM/C → Backup Communication Channel → Remote I/O / Network Devices
Sourcing & Quality Verification
- Source Traceability: All units sourced through documented industrial supply chains; provenance records available on request
- Pre-shipment Inspection: Visual inspection for physical damage, label authenticity, and connector integrity
- Functional Testing: Available upon request for critical applications (specify at time of inquiry)
- Packaging: Anti-static ESD packaging with moisture barrier; double-boxed for international shipments
- Warranty: 90-day replacement warranty against DOA; extended warranty available — contact sales
- Counterfeit Mitigation: Label verification, date-code cross-reference, and physical inspection protocols applied to every unit
Procurement Process
- Submit Inquiry: Contact support@konmask.com with your required quantity, delivery timeline, and any testing requirements
- Receive Quote: Formal quotation issued within 1 business day including unit price, lead time, and shipping options
- Order Confirmation: Purchase order accepted via email; proforma invoice issued for prepayment or net-terms accounts
- Quality Check & Dispatch: Pre-shipment inspection completed; tracking number provided within 24 hours of dispatch
- Delivery & Support: Post-delivery technical support available; RMA process initiated within warranty period if required
Technical FAQ
Q: Is the 1785-BCM/C compatible with all PLC-5 processor variants?
A: The BCM/C is designed for the PLC-5 family. Compatibility depends on the specific processor model and firmware revision. Consult the Allen-Bradley 1785-BCM product compatibility matrix or contact Konmask technical support for confirmation.
Q: Can this module be used in a non-redundant PLC-5 system?
A: Yes, the 1785-BCM/C can be installed in a standard (non-redundant) PLC-5 chassis to add backup communication capability without requiring a full redundant processor pair.
Q: What programming software is required for configuration?
A: RSLogix 5 (or legacy A-B 6200 series software) is required for configuration and diagnostics. The module does not require separate configuration in most standard backup applications.
Q: Do you offer functional testing before shipment?
A: Yes. Functional bench testing is available upon request. Please specify this requirement at the time of inquiry so it can be included in the quotation.
Q: What is the lead time for this module?
A: Standard lead time is 3–7 business days for in-stock units. For urgent requirements, expedited processing is available — contact us directly.
Q: Is this a new or refurbished unit?
A: Konmask supplies both new-surplus and professionally refurbished units depending on availability. Unit condition is clearly stated in the quotation. All units pass pre-shipment inspection regardless of condition grade.
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