1785-L46B Allen-Bradley PLC-5/46 Enhanced Processor 48K Protected Memory

Core Engineering Brief

• The 1785-L46B is a high-performance PLC-5/46 Enhanced Controller designed for large-scale automation.
• This chassis-based processor features 48 Kilowords of battery-backed static RAM and integrated Protected Memory.
• It supports a massive 2048 I/O capacity, providing the computational density required for complex multi-rack configurations.
• The 1785-L46B achieves rapid logic execution at 0.5 ms per Kword, ensuring high-speed processing for critical loops.

Global PLC Spare HUB's Insight

• Engineers prioritize the 1785-L46B for legacy system expansions where data security and proprietary logic protection are mandatory.
• The "B" designation indicates the module's robust protected memory, which safeguards control routines from unauthorized modification.
• Our technical team notes that its four configurable DH+/RIO ports offer unmatched flexibility for bridging distributed plant-wide networks.
• This processor is an ideal central hub for integrating diverse 1771, 1794, and 1746 I/O systems across complex architectures.

Technical Specification Matrix

• Manufacturer: Allen-Bradley / Rockwell Automation
• Model: 1785-L46B
• Series: PLC-5/46 Enhanced
• User Memory: 48,000 Words (Static RAM with Protection)
• I/O Capacity: 2048 Max (Any combination) or 2048 In + 2048 Out (Complimentary)
• Communication: 4 x Data Highway Plus (DH+) / Remote I/O (RIO)
• Serial Port: 1 x 9-pin D-shell (RS-232, RS-422, RS-423)
• Scan Time: 0.5 ms/Kword (Bit Logic); 2 ms/Kword (Typical)
• Backplane Draw: 3.3A @ 5V DC
• Thermal Dissipation: 59.04 BTU/hr (17.3 Watts)
• Addressing: Supports 2-slot, 1-slot, and 1/2-slot hardware addressing
• Clock Accuracy: +/- 5 minutes per month at 60 degrees Celsius

Advanced Diagnostic Capabilities

• Integrated status LEDs provide real-time feedback on CPU health, force conditions, and battery status.
• Channel indicators monitor communication traffic and link health for all DH+ and RIO ports.
• The 1785-L46B provides internal fault logs accessible via RSLogix 5 for rapid troubleshooting.
• Hardware keying and isolation tests (up to 1000V) ensure the module is protected against installation errors and surges.

Target Systems and Application Scenarios

• Automotive Assembly: Coordinating complex robotics interlocks and multi-station conveyor systems.
• Process Security: Securing sensitive batch formulas and proprietary control logic in pharmaceutical plants.
• Remote Infrastructure: Managing up to 32 universal remote I/O chassis per link in distributed facilities.
• System Bridges: Interfacing legacy DH+ segments with modern PC-based supervisory and data acquisition systems.

Global Logistics and Support

• Warranty: All units are protected by a professional 12-month quality guarantee.
• Express Delivery: Global shipping supported via FedEx, UPS, and DHL.
• Order Fulfillment: Rapid dispatch within 24 to 48 hours from our central stock.
• Package Contents: One (1) 1785-L46B PLC-5/46 Processor module.

Selection Guide & FAQ

• Selection Advice: Use the 1/2-slot addressing mode if you need to maximize I/O density with 32-point modules.
• Selection Advice: Always pair with a 1770-XYC battery to maintain the 48K protected memory during power cycles.

• Question: What is the specific benefit of "Protected Memory" in the 1785-L46B?
• Answer: It allows you to lock specific program blocks, ensuring that critical safety or proprietary logic cannot be altered accidentally.

• Question: Can this controller manage I/O in different chassis types?
• Answer: Yes, it is compatible with 1771, 1794 (Flex I/O), 1746 (SLC), and 1791 (Block I/O) systems via Remote I/O.

• Question: Is the front-panel serial port capable of DF1 protocol?
• Answer: Absolutely. The 9-pin serial port supports DF1 in both full and half-duplex modes for modem or PC connections.

• Question: How many Remote I/O racks can one 1785-L46B support?
• Answer: It supports up to 61 I/O chassis total, with 60 of those typically configured as Remote I/O racks.

• Question: Can I use EEPROM modules for program backup with this model?
• Answer: Yes, it is compatible with 1785-ME32, -ME64, and -M100 memory modules for non-volatile backup.

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