Is Your Legacy Machine Control Holding Production Hostage?
When a compact controller fails on a packaging line or a remote wellhead panel, every hour of downtime erodes margin. The Allen-Bradley 1764-28BXB — a MicroLogix 1500 base controller unit from Rockwell Automation — was engineered for exactly those tight, practical control jobs. It packs 28 digital I/O points into a DIN-rail-mountable base unit, and it remains a familiar sight in oil, gas, and general industrial automation cabinets.
Please note: this model is discontinued (discontinuation date 2017-06-30). Rockwell lists the MicroLogix 1400 (1766-L32xxxx) and CompactLogix L1/L2 as replacements. For current availability and replacement options, contact Oil AutoTech directly.
What the 1764-28BXB Delivers
The 1764-28BXB is a processor/controller base unit in the Bulletin 1764 family. Its 28 I/O split as 16 inputs and 12 outputs gives machine builders a balanced point count for small-to-mid control tasks. The input side includes 8 standard plus 8 high-speed (20 kHz) inputs — useful for counting, pulse capture, and fast event detection without adding specialty cards. Outputs combine 6 relay plus 6 FET types, so you can drive mixed loads from one compact base.
Power is 24V DC, and the unit includes an RS-232 port for programming and serial communication. Expansion is a strong point: the base supports up to 512 I/O, letting a single controller grow with the machine instead of forcing a platform change.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | 1764-28BXB |
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Series | MicroLogix 1500 / Bulletin 1764 |
| Product Type | Processor / Controller (Base Unit) |
| Total I/O | 28 (16 in / 12 out) |
| Inputs | 8 standard + 8 high-speed (20 kHz) |
| Outputs | 6 relay + 6 FET |
| Power | 24V DC |
| Communication | RS-232 |
| Expansion | Up to 512 I/O |
| Lifecycle Status | Discontinued (2017-06-30) |
| Replacement | MicroLogix 1400 or CompactLogix L1/L2 |
Where It Fits on the Plant Floor
Oil and gas wellhead panels. The 24V DC supply matches typical instrument power, and the high-speed inputs handle flow-meter pulses. The relay/FET output mix drives valves and pilot devices without extra interface hardware.
Compact machine control. Packaging, labeling, and small assembly cells benefit from the 28-point density and DIN-rail mounting. The RS-232 port keeps programming and serial device links straightforward.
Expansion-ready retrofits. Because the base scales to 512 I/O, a line that outgrows its original point count can add I/O rather than replace the controller — a practical cost saver when budgets are tight.
Integration and Programming Notes
The 1764-28BXB programs with RSLogix 500 / RSLogix Micro and shares the SLC 500 instruction set, so technicians already familiar with that environment can work quickly. The ladder program and data reside in nonvolatile memory. Serial communication runs over RS-232; if you need to connect to a modern network, confirm cabling and any gateway requirements with your supplier before ordering.
Sourcing a Discontinued Controller
With production discontinued in 2017, the practical question is availability, not specification. Oil AutoTech specializes in fast-dispatch spares for oil, gas, and industrial automation — ready-to-ship stock and hands-on technical selection help. Contact Oil AutoTech today for pricing and availability.
Please verify current lifecycle status and availability with Oil AutoTech before ordering.
