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Bulletin 1785 PLC-5 Programmable Logic Controller System

PLC-5 Control System

Bulletin 1785 PLC-5® programmable logic controllers (PLCs) offer flexibility in programming, network, and I/O. Designed for larger sequential and regulatory control applications with specialized I/O requirements, PLC-5 control systems bring together existing and new systems through networks such as EtherNet/IP™, ControlNet™, and DeviceNet™.  Embedded network ports in PLC-5 controllers enable connectivity to a wide range of devices including MicroLogix™, SLC™ 500, CompactLogix™, and ControlLogix® controllers, letting you expand your control system without additional training investments.

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  • Reliability with a Mean Time Between Failure (MTBF) rating that exceeds 400,000 hours
  • 6 K words through 100 K words user memory

Backup options:

  • ControlNet™ Hot Backup module provides control of outputs if the primary controller shuts down
  • PLC-5® Backup Communication module helps increase the fault tolerance of systems controlling I/O on a remote I/O link

I/O support:

  • Monitor and control I/O across ControlNet, DeviceNet™, and Universal Remote I/O links
  • Forcible I/O ranges from 512 through 3072 I/O
  • Maximum remote I/O locations ranges from 5 through 125

Communication ports:

  • On-board ports for DH+, Universal Remote I/O, and RS-232-C/RS-422-A/RS-423-A communication
  • Ethernet or ControlNet dual-media ports included on some controllers
  • Separate modules provide additional communication ports

Additional Information

Our Migration Solutions programs and services will help you leverage the investments you've made in knowledge and equipment when you decide it's time to migrate.

1785 PLC-5 Controllers

Bulletin 1785 PLC-5® controllers are available in a range of I/O capacity and memory sizes. Our controllers have on-board Universal Remote I/O scanner ports and optional communication modules. You can connect our controllers in a variety of networks for distributed processing and I/O control. Selected models of PLC-5 controllers have on-board ports for Ethernet™, ControlNet™, or Extended Local I/O communication.


The PLC-5® system requires a 1771 chassis to contain the various modules. Chassis are available in sizes up to 16-slots to fit your application requirements. The backplane provides a communication path between the I/O modules and either the controller or the I/O communication adapter module.


Bulletin 1771 PLC-5® Communication Modules let you add another communication port to the PLC-5 controller. This adds network capability beyond the available on-board ports.

Power Supplies

Bulletin 1771 PLC-5® power supplies provide 5V DC to power installed controllers or communication adapters and I/O modules in a 1771 chassis. Both chassis-based and stand-alone power supplies are available. They support a range of AC and DC input voltages.


Use RSLogix 5 programming software to program your PLC-5® system. Programs developed with A.I. Series PLC-5 software and 6200 software can be reused in RSLogix 5 software.

The controllers and modules you select, along with your network configuration, determine what additional software packages you need to configure and program your system. Additional required software may include RSNetWorx network configuration software and RSLinx communication software.

Learn More

Additional software products are available from Rockwell Software.


1785 PLC-5 Programmable Controllers Selection Guide1785-SG001
More PLC-5 System publications in Literature LibraryAll Languages

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Product Certifications

See our Product Certification site for Declarations of Conformity, certificates and other certification details.

Configuration & Selection Tools

Other Resources

  • Knowledgebase — Visit our online resource for technical information, support chat and forums, software updates, and product safety advisories/notices.