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1785-L20B | Allen-Bradley PLC-5/20 Controller 16K Word SRAM with DH+/RIO/Serial Ports
- Regular price
- $1,299.00
- Sale price
- $1,299.00
- Regular price
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Product Description P/N: 1785-L20B
Description
The Allen-Bradley 1785-L20B is a PLC-5/20 processor equipped with 16K words of user SRAM and multiple embedded communication channels. It supports DH+, Remote I/O, and RS-232/RS-422/423 serial connectivity, enabling flexible integration into legacy and distributed PLC-5 automation architectures.
Technical Specifications
| Condition | New/Never Used Surplus |
| Brand | Allen-Bradley |
| Category | Drives |
| Part Number | 1785-L20B |
| Subcategory | Programmable Logic Controller |
| Series | PLC-5 |
| Processor Type | PLC-5/20 |
| Memory Capacity | 16K Words SRAM |
| Battery Backup | Yes (1770-XYC) |
| EEPROM Support | 1785-ME16/32/64/100 |
| Max Total I/O | 512 (any mix) or 512 in + 512 out (complementary) |
| Max I/O Chassis | 13 Total (12 Universal Remote) |
| Communication Ports | 1 DH+ Fixed; 1 DH+/RIO; 1 Serial (RS-232/422A/423) |
| Backplane Current Load | 2.3 A at 5 VDC |
| Power Dissipation | 12 W |
| Operating Temperature | 0 to 60 °C |
| Storage Temperature | –40 to 85 °C |
| I/O Scan Time per Rack | 10 ms @ 57.6 kb/s; 7 ms @ 115.2 kb/s; 3 ms @ 230.4 kb/s |
| Supported Power Supplies | 1771-P4S, P6S, P4S1, P6S1 |
| Module Type | Standard Processor |
| Remote I/O Capacity | Up to 12 RIO Chassis |
| Control Coprocessor Port | Yes |
Information About 1785-L20B
The 1785-L20B is part of the PLC-5 family, a long-standing series of modular controllers designed for mid-range industrial automation. Its architecture includes dedicated Data Highway Plus (DH+) communication, a configurable DH+/Remote I/O channel, and a serial interface to support programming, peer networking, and I/O data exchange. The controller features 16K words of battery-backed volatile memory and can be expanded with optional EEPROM modules for nonvolatile program retention. Typical applications include process automation, material handling, and large discrete systems that require multi-rack I/O distribution across Remote I/O networks.
Key Features:
- 16K word user memory: Battery-backed SRAM for program and data retention.
- DH+ and Remote I/O support: Provides two channels for peer-to-peer and distributed I/O networks.
- Configurable serial port: Supports RS-232, RS-422A, and RS-423 communication standards.
- Multi-rack I/O capability: Supports up to 13 total I/O chassis with 12 remote locations.
- Optional EEPROM backup: Compatible with 1785-ME16, ME32, ME64, and ME100 memory modules.
- Three-position key switch: Enables RUN, PROGRAM, and REMOTE operating modes.
- Status and diagnostic indicators: Provides visual monitoring of communication, battery, and processor state.
- Compatible with PLC-5 system power supplies: Works with 1771-series chassis and power modules.
The 1785-L20B delivers the reliability and precision required for distributed PLC-5 control systems and complex industrial automation networks.
Description
The Allen-Bradley 1785-L20B is a PLC-5/20 processor equipped with 16K words of user SRAM and multiple embedded communication channels. It supports DH+, Remote I/O, and RS-232/RS-422/423 serial connectivity, enabling flexible integration into legacy and distributed PLC-5 automation architectures.
Technical Specifications
| Condition | New/Never Used Surplus |
| Brand | Allen-Bradley |
| Category | Drives |
| Part Number | 1785-L20B |
| Subcategory | Programmable Logic Controller |
| Series | PLC-5 |
| Processor Type | PLC-5/20 |
| Memory Capacity | 16K Words SRAM |
| Battery Backup | Yes (1770-XYC) |
| EEPROM Support | 1785-ME16/32/64/100 |
| Max Total I/O | 512 (any mix) or 512 in + 512 out (complementary) |
| Max I/O Chassis | 13 Total (12 Universal Remote) |
| Communication Ports | 1 DH+ Fixed; 1 DH+/RIO; 1 Serial (RS-232/422A/423) |
| Backplane Current Load | 2.3 A at 5 VDC |
| Power Dissipation | 12 W |
| Operating Temperature | 0 to 60 °C |
| Storage Temperature | –40 to 85 °C |
| I/O Scan Time per Rack | 10 ms @ 57.6 kb/s; 7 ms @ 115.2 kb/s; 3 ms @ 230.4 kb/s |
| Supported Power Supplies | 1771-P4S, P6S, P4S1, P6S1 |
| Module Type | Standard Processor |
| Remote I/O Capacity | Up to 12 RIO Chassis |
| Control Coprocessor Port | Yes |
Information About 1785-L20B
The 1785-L20B is part of the PLC-5 family, a long-standing series of modular controllers designed for mid-range industrial automation. Its architecture includes dedicated Data Highway Plus (DH+) communication, a configurable DH+/Remote I/O channel, and a serial interface to support programming, peer networking, and I/O data exchange. The controller features 16K words of battery-backed volatile memory and can be expanded with optional EEPROM modules for nonvolatile program retention. Typical applications include process automation, material handling, and large discrete systems that require multi-rack I/O distribution across Remote I/O networks.
Key Features:
- 16K word user memory: Battery-backed SRAM for program and data retention.
- DH+ and Remote I/O support: Provides two channels for peer-to-peer and distributed I/O networks.
- Configurable serial port: Supports RS-232, RS-422A, and RS-423 communication standards.
- Multi-rack I/O capability: Supports up to 13 total I/O chassis with 12 remote locations.
- Optional EEPROM backup: Compatible with 1785-ME16, ME32, ME64, and ME100 memory modules.
- Three-position key switch: Enables RUN, PROGRAM, and REMOTE operating modes.
- Status and diagnostic indicators: Provides visual monitoring of communication, battery, and processor state.
- Compatible with PLC-5 system power supplies: Works with 1771-series chassis and power modules.
The 1785-L20B delivers the reliability and precision required for distributed PLC-5 control systems and complex industrial automation networks.