Chapter 1
What is Wi-Fi?
Connecting devices to a network without using a LAN cable.
Using Wi-Fi, you can connect devices such as computers, smartphones, tablets, and instrument to a network using radio waves, without directly connecting them with LAN cables.
While smartphones and computers are commonly used at home to connect to the internet, in factories they are also used to connect instrument and data loggers to computers, and to collect measurement data.
Wi-Fi and the internet are different things.
Just because you're using Wi-Fi doesn't necessarily mean you're connected to the internet.
For example, within a factory, it's possible to connect only instrument and monitoring PCs via Wi-Fi, without configuration to the external internet.
| words | Role | Simple image |
|---|---|---|
| Wifi | Connect to the LAN using radio waves. | Making a LAN cable wireless |
| LAN | A network within a limited area, such as buildings or facilities. | Network within the facility |
| internet | Connecting networks around the world | Networks that connect to the outside of the LAN |
What does Wi-Fi stand for?
Wi-Fi is not an abbreviation of "Wireless Fidelity." The name Wi-Fi itself is a brand name adopted as an easy-to-remember name to promote the widespread use of wireless LAN products.
When trying to understand Wi-Fi, it's enough to know that it's "used to connect compatible devices wirelessly via a LAN," rather than worrying about the origin of the name.
Chapter 2
What's the difference between Wi-Fi and wireless LAN?
In everyday conversation, "Wi-Fi" and "wireless LAN" are often used interchangeably, but strictly speaking, their scopes are slightly different.
Wireless LAN
This is a general term for networking methods that use wireless communication instead of cables to build a LAN.
Wifi
This is a widely used name for certification and branding that verifies interoperability of devices utilizing IEEE 802.11-based wireless LAN technology.
Therefore, it has become widely established to refer to wireless LANs used by general personal computers, smartphones, and access points as "Wi-Fi."
Chapter 3
What are routers, access points, and SSIDs?
When using Wi-Fi, you'll encounter terms like "router," "access point," and "SSID." Understanding their respective roles makes it much easier.
| Name | Role |
|---|---|
| Access point | A connection point for Wi-Fi-enabled devices to connect to a LAN wirelessly. |
| router | A device that relays data between different networks. |
| Wireless LAN router | A device that integrates the functions of a router and a Wi-Fi access point. |
| SSID | A name to identify the Wi-Fi network you are connecting to. |
While home Wi-Fi routers often have multiple functions integrated into a single unit, making the differences less noticeable, factories sometimes have separate access points and routers.
Chapter 4
What's the difference between 2.4GHz and 5GHz?
Wi-Fi utilizes multiple frequency bands. The most common are the 2.4GHz and 5GHz bands.
| Item | 2.4GHz band | 5GHz band |
|---|---|---|
| How it arrives | It can reach relatively far distances. | More susceptible to interference from obstacles than 2.4GHz. |
| congestion | Due to the large number of devices in use, congestion and interference may occur. | It may be easier to avoid congestion than with 2.4GHz. |
| Major features | It is more likely to be a candidate in environments with distance and obstacles. | Candidates are determined based on communication speed and surrounding radio wave conditions. |
It's not as simple as saying "2.4GHz is always the best for factories" or "5GHz is always the fastest." You need to consider factors such as distance, walls, metal structures, surrounding radio waves, and the frequency band supported by the equipment you'll be using before making your selection.
Chapter 5
What's the difference between Wi-Fi and wired internet?
Wi-Fi isn't the only way to connect instrument. Serial communication methods such as Ethernet (LAN) and RS-485 are also widely used in industrial settings.
| Method | Features | Way of thinking |
|---|---|---|
| Wifi | Connect to LAN via radio waves | Easy to reduce wiring |
| Ethernet | Connect to the network using a LAN cable. | It is easy to establish stable communication with fixed equipment. |
| RS-232C | Relatively simple one-to-one serial communication | Applications for directly connecting devices |
| RS-485 | It can be used with multiple devices and over relatively long distances. | Widely used in industrial applications where multiple instrument are connected. |
Just because something is wireless doesn't necessarily mean it's convenient.
Wi-Fi is effective in locations where wiring is difficult or for mobile devices, but wired communication such as Ethernet may be more suitable when fixed wiring is possible.
When choosing a communication method, it's important to consider factors such as required distance, stability, wiring, number of devices, and compatibility with existing equipment, rather than simply selecting a new method because it's new.
Chapter 6
Main reasons why Wi-Fi won't connect
The distance is far
Radio waves weaken with distance. Shortening the distance between the access point and the device may improve the signal strength.
There are walls and metal
Concrete walls, metal shelves, and large equipment can block or reflect radio waves.
Some have a high moisture.
Objects containing a lot of water can also affect radio waves. Caution should be exercised if tanks, pipes, products, or plants are located in the communication path.
Interferes with surrounding radio waves
In environments where many devices use the same frequency band, communication may become congested or unstable.
Chapter 7
Why is it sometimes difficult to connect to Wi-Fi in factories?
The radio wave environment in factories and warehouses can differ significantly from that of offices and typical homes. Large metal equipment, shelving, building structure, and equipment operation all have a particular impact on communication.
| On-site | Things that are likely to happen | Points to check |
|---|---|---|
| manufacturing factory | Large equipment and metal objects can block or reflect radio waves. | Avoid the area behind the equipment and change the installation height and position. |
| warehouse | The radio wave environment changes depending on the metal shelves and the items stored inside. | Don't judge solely based on whether the shelves are empty. |
| Tank and piping area | Affected by metals and liquids | Check the positional relationship with the access point. |
| Greenhouse | It is affected by factors such as metal frameworks and plant moisture. | We also check for changes due to the seasons and plant growth. |
In factories, changes in equipment and inventory layout can cause communication that worked fine at the time of implementation to become unstable later on. It is important to check the communication environment under actual operating conditions.
Chapter 8
How do you choose between Wi-Fi, wired, and other wireless connections?
For factory measurement and monitoring, Wi-Fi is not the only wireless communication option. Depending on the application, wireless equipment using the 920MHz band or other frequencies may be more suitable.
| Method | Suitable situations | Things I want to confirm |
|---|---|---|
| Wifi | I want to utilize the existing LAN and connect PCs and network devices. | Radio wave environment, frequency band, security |
| Ethernet | I want to build a stable network using fixed equipment. | Wiring routes, ports, network configuration |
| RS-485, etc. | I want to connect instrument in a relatively simple way. | Wiring distance, number of units, communication protocol |
| 920MHz band, etc. | I want to wirelessly collect small amounts of measurement data from a relatively wide area. | Communication speed, transmission interval, compatible devices, installation environment |
The choice of communication method isn't solely determined by whether it's wireless or wired. It's easier to choose if you first clarify what you need, where you'll be collecting it from, how often, and how many devices you'll be using.
Chapter 9
When using Wi-Fi in a factory, make sure to check the security settings.
When using Wi-Fi in factories or research facilities, it's important not only to consider whether the signal reaches the area, but also who can connect to the network.
- Do not use the default password.
- Manage the devices and users you use
- Do not allow unnecessary external connections.
- Review the company's network and information security policies.
- Check the update and maintenance procedures for equipment and access points.
When connecting monitoring systems or measuring instruments to the company network, it is important not to make decisions solely with the measurement personnel, but to confirm the connection conditions with the IT department and network administrator before proceeding.
Chapter 10
Steps to check when your Wi-Fi won't connect.
- Check that the SSID you want to connect to and the settings are correct.
- Move the device closer to the access point and observe the changes.
- Check for obstacles such as walls, metal shelves, large equipment, and tanks.
- Try changing the position, height, and orientation of the equipment or access point.
- Check the frequency band you are using, such as 2.4GHz or 5GHz.
- Check if there are many other devices in the vicinity that use the same frequency band.
- If the problem persists, consider adding more access points or reviewing the communication method itself.
Radio wave conditions vary greatly depending on the installation location. Sometimes, simply moving the device by a few centimeters or even a few meters can improve communication quality.
FAQ
Frequently Asked Questions about Wi-Fi
What is Wi-Fi in simple terms?
This system is used to connect computers, smartphones, instrument, and other devices to a LAN using radio waves, without the need for LAN cables.
Are Wi-Fi and wireless LAN the same thing?
While often used interchangeably in everyday conversation, wireless LAN is a general term for methods of building a LAN wirelessly. Wi-Fi, on the other hand, is a widely used certification and brand for interoperability that utilizes IEEE 802.11 wireless LAN technology.
Are Wi-Fi and the internet different?
That's incorrect. Wi-Fi is a system for wirelessly connecting devices to a LAN, while the internet is a system for connecting to an external network. There are also Wi-Fi networks that do not connect to the internet.
Is Wi-Fi an abbreviation for Wireless Fidelity?
No. Wi-Fi is not an official abbreviation for Wireless Fidelity.
Which is better, 2.4GHz or 5GHz?
There's no single answer. 2.4GHz has a relatively long range, but it can be affected by interference from surrounding devices. 5GHz is more susceptible to interference from obstacles than 2.4GHz, so you should choose based on distance, equipment placement, and surrounding radio waves.
Is a wired LAN connection better than Wi-Fi in a factory setting?
It depends on the application. If you prioritize stable communication and easy wiring in a fixed installation, a wired LAN may be suitable. If you want to increase flexibility in equipment placement or if wiring is difficult, Wi-Fi is effective.
Are RS-232C, RS-422A, and RS-485 considered Wi-Fi?
No. These are all typical serial communication methods, and are different from Wi-Fi. They are still widely used in industrial instrument.
What should I check first if I can't connect to Wi-Fi?
First, check the settings and distance, then, in order, check for obstacles such as walls and metal equipment, the frequency band being used, and surrounding radio wave congestion. This will make it easier to pinpoint the cause.
Summary
Wi-Fi is chosen not only for its convenience, but also as a communication method suited to the specific site.
Because Wi-Fi allows devices to connect to a network without using LAN cables, it can be used not only for PCs and smartphones, but also for factory instrument and monitoring systems.
On the other hand, in factories, the radio wave environment can vary greatly due to metal equipment, walls, tanks, and surrounding wireless devices. Both 2.4GHz and 5GHz have their own characteristics, and Wi-Fi is not always optimal in all locations.
When connecting instrument, it's important to understand the characteristics of various protocols such as Wi-Fi, Ethernet, and RS-485, and then choose the appropriate one based on factors like distance, number of devices, communication volume, wiring, and connection requirements with existing equipment.
I need advice on how to connect instrument.
Knowing instrument to be used, the installation location, the connection distance, the presence of walls or metal structures, and the required communication frequency will make it easier to organize connection methods, including Wi-Fi and wired communication.
I need advice on connecting instrument
