01 — WHAT IS A NETWORK
Why devices need to talk, and how they do it.
Estimated 6 minutes.
What is a network?
A network is two or more devices that exchange information. Your phone and a Wi-Fi router. A PLC and an HMI. A sensor and a controller. Anywhere data flows between devices, there is a network.
Two devices, one cable, some data.
A PLC and a laptop, exchanging data over a cable.
Build the smallest network.
Two devices. No cable. Click Connect and watch what happens. Then click the cable to cut it.
Wires or wireless?
Networks use wires (Ethernet, fiber, serial cables) or radio waves (Wi-Fi, Bluetooth, cellular). On the plant floor, almost everything is wired. Wireless is rare in critical control.
Why wired?
Why do you think factories prefer wired networks?
- Speed
- Reliability
- Security
- All of the above
Devices need rules.
Two devices cannot just exchange random bits and hope it works. They need agreed-upon rules — formats, timings, who speaks first. These rules are called protocols.
A protocol sits between devices.
One task, many protocols.
When your laptop loads a webpage, dozens of protocols cooperate. Wi-Fi to talk to the router. IP to find the server. TCP to send data reliably. HTTP to format the request. Each layer has a job.
Tap each layer.
Real networks stack protocols. Tap one to see what it does.
Industrial networks are similar.
On the factory floor the same model applies. Ethernet at the bottom. IP for addressing. Then a protocol like Modbus or Profinet on top, formatted for industrial data — sensor values, motor commands, alarms.
How many protocols?
A sensor sends a temperature reading to a PLC. How many protocols are involved?
- 1
- 2
- 3 or more
You just learned the foundation.
- A network is devices exchanging data.
- Protocols are the rules they follow.
- Multiple protocols stack to do one task.
Lesson 01 complete.
- You can explain what a network is in one sentence.
- You know why factories prefer wires.
- You understand that a single task uses many cooperating protocols.