ReliaSim® vs Simio
A Digital Twin and Scheduling Platform and a Purpose-Built Line Simulator

Simio builds object-oriented, data-driven simulation models and extends them into planning and scheduling. ReliaSim is built for production lines and the supply chains they feed, modeled as flow from each line’s own stop history. This page sets out where each fits.

What Simio is built for

Simio says it “creates object-oriented, data-generated, and data-driven simulation models” and leads with “Intelligent Digital Twin Simulation” powered by Simio Discrete Event Simulation (Simio home page). Its products include the Simio Process Digital Twin, Advanced Planning & Scheduling (APS) and a DDMRP solution, with 3D visualization, Python integration and an NVIDIA Omniverse extension. Simio offers a “free, full-featured, time-limited” trial edition, and commercial use requires a purchased license (Simio commercial download).

Where Simio is the better fit

• Scheduling from the model. If you want the same model to produce detailed production schedules day to day, Simio’s APS is built for that.
• Models generated from enterprise data. Building and refreshing large models from data tables and connected systems is central to Simio’s approach.
• Demand-driven planning. Its DDMRP solution covers buffer positioning in the planning sense, which ReliaSim doesn’t address.
• Many kinds of system. Simio is used across manufacturing, healthcare, warehousing and distribution.

ReliaSim doesn’t try to be a scheduling system.

Where ReliaSim fits

The price is on the page

A ReliaSim desktop license is $8,000 per user per year, and you can buy it online. ReliaStats, the companion tool that fits failure and repair distributions from your stop data, is $1,800 per user per year, and its Designer is free. The Sandbox and the desktop demo cost nothing. Every price is on the pricing page.

Discrete rate, built for high-speed lines

A discrete event model moves each unit through the line as its own event. On a line that makes hundreds of units a minute, that’s a great many events per simulated hour. ReliaSim uses discrete rate simulation, which models material as flow at rates and changes state only when a rate changes: a machine stops or restarts, or a buffer fills or empties. The work grows with the number of stops, not the number of units. A thousand one-year runs of the five-machine demo bottling line take about two and a half minutes on a laptop, or 0.154 seconds per simulated year. That speed is what makes sweeps practical: the buffer study behind how big should a buffer be? is 7,770 runs in 31.8 seconds. Discrete rate vs discrete event explains the difference in full.

Validated before it predicts

A published food plant model, from Fischel and Lange at the 2020 Winter Simulation Conference, was rebuilt in ReliaSim and independently validated by Tom Lange. It came within 1% of the plant’s measured OEE (the validation study). Every ReliaSim model follows the same order: reproduce the line’s own history, failure mode by failure mode, then ask what-if. How to check a digital twin’s accuracy claim sets out the test, for any vendor.

Your data stays on your machine

ReliaSim is desktop software for Mac and Windows. Models are files on the modeler’s own machine, and it works air-gapped. Security and deployment covers what IT usually asks.

At a glance

Using both

A plant that schedules in one system can still test a line change in ReliaSim first: what a new buffer, a faster machine or a fixed failure mode returns, given the line’s own stop history. The schedule then runs on a line whose real capacity is known.

How to choose

If you need the model to run the plant’s schedule every day, start with a scheduling platform. If you need to know what a production line will really make, and what each fix is worth, start with a model built from its stops and checked against its measured OEE. Simio is referenced here for identification only; no affiliation or endorsement is implied.