Allen-Bradley 1769-L35CR CompactLogix L3 Controller

The Allen-Bradley 1769-L35CR, also cataloged as the 1769-L35CR CompactLogix L3 Controller, operates as a dedicated hardware component for real-time logic execution and deterministic network orchestration within CompactLogix automation architectures.

Hardware Specifications

Backplane Bus Communication Velocity & ControlNet Deterministic Networks

The unit communicates with local 1769 Compact I/O modules across the 1769 backplane bus, managing I/O data scanning at high bus communication velocity. On-board dual ControlNet ports allow participation in scheduled, deterministic network topologies where cross-controller messaging and remote I/O data exchanges adhere to exact scheduled timing intervals without packet collision. The dedicated Network Access Port (NAP) provides local node access for engineering workstations without interrupting active network traffic.

Frequently Asked Questions

Q: How does the controller handle redundant ControlNet network media connections?

A: Dual BNC ControlNet connectors allow direct connection to redundant physical channels (Channel A and Channel B). The hardware continuously transmits data over both media channels and automatically selects the primary signal path without delaying scan cycles.

Q: What limits apply to expanding local 1769 Compact I/O modules on the 1769-L35CR?

A: The controller supports up to 16 local I/O modules divided across a maximum of 3 expansion banks. Each bank requires its own power supply, and total module distance ratings relative to the power supply must not be exceeded.

Field Installation Guidelines

Mount the controller module onto a standard panel backplate or 35 mm DIN rail inside an industrial enclosure. Ensure the right-side bus connector mates firmly with adjacent 1769 Compact I/O modules or expansion cables before locking the top and bottom panel-mounting latches.

For cabinet commissioning and communication setup:

1. Connect ControlNet coaxial cables using standard RG-6 BNC connectors directly to ports A and B.
2. Ensure the 1769-ECR or 1769-ECL end cap is installed at the end of the local 1769 backplane bus to maintain backplane signal integrity.
3. Terminate serial cables using shielded twisted pair to the RS-232 port for point-to-point configuration or ASCII communication.
4. Connect enclosure earth ground to the mounting rail or chassis terminal using minimum 14 AWG copper wire to maintain electromagnetic compatibility limits.