Wireless can be broken down into two types: public and proprietary
In a proprietary system, such as frequency-hopping spread spectrum (FHSS), the wireless modules must all belong to the same platform from the same manufacturer. Products from each manufacturer communicate differently and have differentiating features from one another. A proprietary system creates an inherent level of security since a hacker can’t add any old module to the wireless network.
With a public system (such as Wi-Fi at Starbucks), users can generally intermix wireless modules from different manufacturers.
Next you need to decide the industrial protocol to be used — Modbus, Ethernet/IP, etc. The way you plan on implementing the protocol over the wireless network could help determine which wireless technology is the best fit.
Before purchasing any wireless network it is a great idea to test it. Your area may look free of obstructions, but you never know until you do a trial. Most manufacturers have a demo set that makes it easy not just to see that signals make it from one side to the other but you can also see the strength of the signal which may help determine the technology of choice.
What about security?
While wireless presents special challenges, there are several ways to increase security. First, make sure the equipment is located in a physically secure area. Put locks on the panel doors, and limiting access to only approved personnel. Next, change the default login information to the Web-based management of the wireless module if applicable. Not changing the default login makes for easy access by just reading the user manual.
If a proprietary wireless technology will work for you, this adds a level of protection since it restricts the devices on the network to single manufacturer’s wireless platform. Gaining access to the network requires knowledge of the platform and module you are using.
Finally you can turn on the over-the-air encryption. Using the WPA2-AES level of security is considered “un-hackable” by today’s standards. When setting up security you should always choose the highest level of encryption available so you have the most secure system.