Allen-Bradley 1769-L24ER-QB1B CompactLogix 5370 L2 Controller

Configured for discrete control execution and network node aggregation, the Allen-Bradley 1769-L24ER-QB1B (1769-L24ER-QB1B CompactLogix 5370 L2 Controller) provides direct physical/electrical execution across embedded digital I/O channels and dual EtherNet/IP communications.

Hardware Specifications

Backplane Bus & Deterministic Network Execution

The processor coordinates real-time signal processing over backplane bus communication velocity frameworks while managing data routing across Profinet / EtherNet/IP deterministic networks. Dual integrated Ethernet ports execute ring topology protocols via Device Level Ring (DLR) functionality, preventing single point network failures without increasing message latency. Firmware flash compatibility across system revisions enables deterministic cyclic data exchange for up to 8 EtherNet/IP nodes and 120 TCP connections. The internal execution engine scales I/O density through 4 local 1769 expansion modules, executing up to 32 user tasks simultaneously while maintaining continuous galvanic isolation between the 24 VDC embedded power supply and backplane logic channels.

Frequently Asked Questions

Q: What network recovery advantages are provided by the dual EtherNet/IP ports on this controller?

A: The dual ports feature embedded Device Level Ring (DLR) capability. When wired in a ring topology, the processor detects single-point cable breaks or node failures and re-routes network traffic in under 3 ms without dropping active TCP or EtherNet/IP I/O connections.

Q: How does the internal power supply limit local 1769 module expansion?

A: The embedded 24 VDC power supply delivers 1.54 A at 5 VDC and 0.95 A at 24 VDC to the backplane, supporting a maximum of 4 local 1769 I/O expansion modules. Adding more than 4 local modules exceeds backplane power bus ratings and requires an independent bank connected via expansion cables.

Field Installation Guidelines

Mount the controller vertically or horizontally on an IEC standard DIN rail, or fasten it directly to an enclosure backplate using M4 panel mounting screws. Maintain at least 50 mm (2 in) of clearance above and below the unit to allow natural convection cooling between 0 and 60 deg C.

Wire the 24 VDC embedded power supply input using 22 to 14 AWG solid or stranded copper conductors rated for 90 deg C. Torque terminal block screws to 0.68 N m (6 lb in) to maintain low-resistance electrical connections.

Route Ethernet communications cabling through CAT5e or CAT6 shielded twisted-pair cables separated from high-voltage AC lines and motor drive leads. Terminate cable shields directly to the cabinet ground bus to mitigate high-frequency electromagnetic noise.