The 1785-L20B is a PLC-5/20 Processor by Allen-Bradley, featuring 16K Word SRAM memory. This controller falls under the PLC 5 Programmable Controller category, designed for various industrial applications.

Key Specifications

• Maximum User Memory Words: 16K
• Total I/O Maximum (Any Mix): 512
• Total I/O Maximum (Complimentary): 512 inputs + 512 outputs
• Communication Ports:
  • 1 DH+ (Fixed)
  • 1 DH+/Remote I/O (Adapter or Scanner)
  • 1 serial port (configurable for RS-232, 423, RS-422A)
• Maximum Number of I/O Racks (Rack Addresses): 4 (0-3)
• Maximum Number of I/O Chassis (Total): 13
• Maximum Number of I/O Chassis (Remote): 12

Additional Information

• Battery-backed static RAM
• EEPROM program backup option using 1785-ME16, -ME32, -ME64, and -M100
• 512 Analog I/O
• I/O Scan Time:
  • 10 ms @ 57.6 kbit/s
  • 7 ms @ 115.2 kbit/s
  • 3 ms @ 230.4 kbit/s
• 1 DH+ and 1 DH+/Remote I/O Channels
• RS-232-C/422-A/423-A Configurable Serial Port
• Backplane Current Load @ 5V: 3.3 A

Miscellaneous

The Allen-Bradley 1785-L20B PLC-5 processors are single-slot modules for 1771 I/O chassis, offering diverse I/O, memory, and communication options. These processors include Data Highway Plus and RS-232-C/422-A/423-A communication ports. Additionally, Ethernet PLC-5 processors have an Ethernet port, and ControlNet PLC-5 processors feature a ControlNet port.