I've got some machines using an ML1100 and others using ML1500 with NetENI. Both use a Hirschmann 5TX switch to join the panelview, plc, and connect to ethernet.

We tend to move lines and equipment around the building a lot. The cost of running ethernet drops or moving them gets expensive.

What do I need to get these on an existing wireless network?

I have used phoenix contact wireless products with no problem, but there are many other options out there. Link below

http://www.phoenixcontact.com/automation/32119_30375.htm

For the ML1100's you will need to place Access Points for them to connect to which will place them on a wireless network. You can do the same for the ML1500's. I looked andt here are no wireless cards for the AB devices. You could use Prolinx Ethernet/IP tp DF1 cards, Lantonix makes a DF1 to Wireless converter as does DIGI. You could also go with GE MDS iNET Radio Modems which can replave the ENI models they also have a line of access Points that can be used for the ML1100's.

Any of the solutions above are going to run $300+ per PLC.

these hook up the the copper connection of the plc's and creates a wireless bridge to the existing wireless network, you do not need a card for the plc's just a interface from plc to wireless network, try downloading the manual for the RAD-80211-XD and take a look. If I am missing something let me know, from your question I take it you are looking for hardware options.

Looks like you have some good answers to your root question so I'll digress to a tangent. Make sure you do a wireless survey before counting on wireless to connect your PLC to the network.

The average coverage circle of a WAP is 300 feet.

It can be even less when you factor in machine steel, catwalk steel and vessel walls.

Don't be surprised if at some point after going wireless you have to add/move a WAP to get the machine to connect.

I'd also advise you have contingency code in your PLC for what to do when comms fail.