Triconex 8111 Expansion Chassis | High-Density I/O Bus

June 15, 2026 • 3 min read • wayne • Guide

Product Summary

The Triconex 8111 expansion chassis provides a high-density I/O configuration for your safety system. It uses six RS-485 ports for triplicated serial communications. This chassis ensures robust data transfer between I/O modules and main processors. Its steel construction offers durability in demanding industrial environments.

Product Procurement & Buyer Guide

Understanding the Triplicated I/O Bus Architecture

The 8111 chassis uses a unique triplicated I/O bus for maximum reliability. Each chassis includes six RS-485 ports at the top left corner. These ports create two sets for channels A, B, and C. This design provides two separate serial communication paths between chassis. You need one cable set for each expansion chassis. The standard cable set (model 9000) has a length of 6 feet. Longer cables are available for your specific layout needs. This architecture guarantees fault tolerance in critical processes.

Data Transfer Speeds and System Integration

The triplicated I/O bus transfers data at 375 kilobits per second. This speed ensures fast communication between I/O modules and processors. The communication bus runs at 2 megabits per second for module links. You must consider these rates for your system timing requirements. The chassis supports a high-density configuration for many I/O points. This design reduces the total number of chassis needed for your project.

Keyswitch Modes for Operational Control

This chassis supports several keyswitch modes for safe operation. The PROGRAM mode allows full control from TriStation for loading. It also permits writes to program variables by external hosts. The STOP mode halts the control program and forces outputs to zero. Non-retentive outputs go to 0, but retentive outputs keep their value. The REMOTE mode allows writes by TriStation and external hosts. However, it does not allow any modification to program logic. These modes help you manage system changes and maintenance safely.

Mechanical Specifications for Installation Planning

The chassis measures 19 inches wide by 22.75 inches high. Its depth is 17.75 inches, making it a standard rack-mount size. The fabrication uses black zinc-plated and welded cold-rolled steel. This material provides excellent strength and corrosion resistance. The main chassis weighs approximately 54.0 pounds. A power module weighs 7.2 pounds for your weight calculations. Main processors weigh 4.7 pounds each for handling purposes.

Ensuring Compatibility with Your Existing System

You must verify compatibility with your current Tricon system hardware. The chassis requires an RXM chassis for the primary module set. Each expansion chassis needs one cable set for proper connection. Use the correct cable model 9000 or specify longer alternatives. The chassis accepts I/O modules weighing between 4.7 and 6.0 pounds. Communication modules weigh 5.0 pounds for your planning. This information helps you design a scalable and reliable system.