Overview
The Allen-Bradley 1785-L30B is a PLC-5/30 processor module designed for mid-to-large-scale industrial automation and control systems. This PLC-5 processor features integrated 32K word user memory, making it suitable for complex process control, data acquisition, and supervisory applications. The module supports installation of up to 29 racks, with 28 racks as Remote racks, enabling distributed control architectures across manufacturing facilities and plant floors.
Key Features
- 32K words of user memory for substantial program and data storage
- Supports up to 1024 I/O devices composed of any combination of discrete and analog input and output devices
- Embedded communication ports: Two DH+/Remote I/O (Adapter or Scanner) ports and one serial port configurable for RS-232 and RS-422A standards
- Capable of implementing Remote I/O architecture by connecting to a maximum of 28 Remote I/O racks using integrated DH+ and Remote I/O (RIO) channels
- Battery-backed module that maintains user and program data stored within the controller’s user memory when power is removed
- User-friendly LED indicators for battery status, controller state, I/O force status, and communication activity; three-position key switch for easy mode selection (Run, PROG, REM)
Technical Specifications
The following specifications apply to the 1785-L30B processor module:
- Processor Type: PLC-5/30 Standard Processor
- User Memory: 32K words SRAM
- Maximum I/O: 1024 total (discrete and analog mixed, or complementary)
- Communication Ports: 2× DH+/Remote I/O, 1× serial (RS-232/RS-422A)
- Remote I/O Racks: Up to 28 remote racks supported
- Backplane Current: Approximately 1.2A @ 5V DC
- Battery Backup: Yes (replaceable, maintains data for extended periods)
- Operating Temperature: 0°C to +60°C
- Mounting: Chassis-based (1771 5-slot or larger)
Typical Applications
The Allen-Bradley 1785-L30B is widely deployed in:
- Manufacturing process control and automation
- Discrete and process industry supervisory control
- Multi-site distributed control with Remote I/O architecture
- Data acquisition and reporting systems
- Machine sequencing and synchronization
- Facility-wide automation integrated with DH+ networks
Compatibility & Replacements
Compatible With
- Allen-Bradley PLC-5 series systems and 1771 I/O chassis
- DH+ (Data Highway Plus) networks and remote I/O architecture
- RS-232 and RS-422A serial communication protocols
- Remote I/O scanners and adapters for distributed control
- Ethernet interface modules for network implementation
- RSLogix 5 programming software for controller configuration and maintenance
Replaces / Drop-In Replacement For
The 1785-L30B is the standard PLC-5/30 processor module from Allen-Bradley. The 1785-L20B has specifications half the capacity of the 1785-L30B, making the 1785-L30B suitable for applications requiring greater memory and I/O capacity. Verify compatibility with your system integrator before ordering replacement or upgrade modules.
Works With
- RSLogix 5 (legacy and current versions)
- Allen-Bradley PLC-5 programming environment
- DH+ protocol and topology
- Remote I/O and scanner architecture
- Serial DF1 protocol (via adapter)
- 1771 series I/O modules and chassis
