Allen-Bradley 1769-L23-QBFC1B CompactLogix Controller

The Allen-Bradley 1769-L23-QBFC1B, also cataloged as the 1769-L23-QBFC1B Processor Module, operates as a dedicated hardware component for executing real-time logic programs and processing field signal channels within CompactLogix systems.

Hardware Specifications

Backplane Bus & Deterministic Network Execution

The processor coordinates real-time logic execution across the 1769 backplane bus communication velocity framework, establishing deterministic signal scan schedules between internal registers and field terminal points. The dual RS232 ports execute point-to-point and multi-drop serial messaging, routing DF1, DH485, and ASCII protocol frames without interrupting local ladder logic execution. System firmware flash compatibility ensures synchronized register mapping across embedded digital I/O, analog channels, and high-speed counter inputs. Internal ASIC components enforce signal isolation across channels, enabling stable I/O density scaling during peak processor instruction execution.

Frequently Asked Questions

Q: What serial protocols can be configured on the two RS232 ports of this module?

A: Port 1 supports DF1 full-duplex/half-duplex, ASCII, and DH485 protocols. Port 2 supports DF1 full-duplex/half-duplex and DH485 protocols. You must configure port parameters directly within RSLogix 5000 / Studio 5000 software to match the field serial device settings.

Q: What wire size and terminal block part number are required for field I/O connections?

A: The controller utilizes the 1769-RTBN18 replacement terminal block. Field wiring requires solid copper conductors ranging from 22 to 14 AWG, rated for an operational temperature limit of 90 deg C.

Field Installation Guidelines

Mount the module on an IEC standard DIN rail or fasten it securely to a backpanel using screws. Confirm that the operating environment inside the enclosure remains within 0 to 60 deg C and relative humidity stays within non-condensing limits.

When wiring field devices, strip copper wire leads to standard length and secure them into the 1769-RTBN18 removable terminal block. Ensure that power wires, analog signal cables, and high-speed counter runs maintain proper physical routing away from high-voltage motor circuits to suppress noise interference.

Connect the dedicated system earth ground directly to the controller grounding terminal using low-impedance ground straps. Ground all analog cable shields at a single point to prevent ground loops and preserve signal conversion accuracy across field input loops.