PLC Chassis | Allen-Bradley 1746-A2 SLC 500 Series

The 1746-A2 is a 2-slot modular chassis designed for the Allen-Bradley SLC 500 programmable logic controller system. It provides the mechanical housing and backplane interconnection for one SLC 500 processor or 1747 I/O adapter module alongside one 1746 I/O module. The backplane distributes logic power provided by an attached 1746 power supply unit directly to the installed modules across its high-speed communication bus.

Backplane Power Distribution and Interconnection

Every slot on the backplane features standard 1746 card guides and socket connectors, allowing backplane communication and power supply feeding. Slot 0 is strictly reserved for the system processor (such as an SLC 5/01, 5/02, 5/03, 5/04, or 5/05) or a remote I/O adapter. Slot 1 accommodates any standard 1746 digital, analog, or specialty I/O module. Power is supplied by mounting a compatible 1746 power supply unit onto the left side of the chassis, which connects directly to the backplane power harness.

System Expansion and Mounting

The 1746-A2 supports standard panel mounting within standard industrial enclosures. For applications requiring more than two slots, multiple 1746 chassis can be interconnected in series using 1746-C9, 1746-C7, or 1746-C16 interconnect cables to form a continuous backplane across up to three chassis, subject to maximum system module limits.

Technical Specifications

Frequently Asked Questions

Q: Can the 1746-A2 chassis be used without a standalone power supply unit? A: No, the 1746-A2 backplane does not generate its own operating voltage. It requires a compatible 1746 power supply unit (such as a 1746-P1, 1746-P2, or 1746-P4) mounted to the left side of the frame to supply 5 VDC and 24 VDC backplane power to installed modules.

Q: Which module must be installed in Slot 0 of the 1746-A2? A: Slot 0 (the leftmost slot) is dedicated to the system controller or remote I/O adapter module. Standard 1746 I/O modules must be installed in Slot 1.