Wireless Ethernet Link

Need to connect a MicroLogix 1100 to an A-B network switch that is about 250 feet away in another building. Running a cable is not feasible. The link would only be used to read data from the ML1100 for display on an HMI that is also part of the main network (non-critical). Looking for an inexpensive way to set this up. If I could run a CAT5 cable that would work for me, so the hardware has to act just like a cable was there. Thanks!!

Cheapest/easiest way would be a pair of 802.11b "wireless bridges". They have minimal configuration, then a wire plugs into the devices on both sides.

You could probably also find cheap directional antennas. Check ebay. Or use a Pringles can.

If you can't run a cable, then you will have to go wireless. The hardware from manufacturers such as Moxa or Hirschman is pretty much the same, but I would suggest having the equipment provider perform a site survey and recommend the appropriate wireless antenna.

Regards

Prosoft has many wireless offerings also. We use them here and they are very reliable.

Hirschman,prosoft,moxa would be best choice as they are engineered and hardened for industrial applications and designed to work with plc's and control systems in mind.

For critical applications, I recommend Data-Linc and Prosoft wireless IP products. They're rugged, reliable, and built by companies who understand industrial protocols and applications.

The extremely inexpensive method is to use surplus 802.11b or 802.11g WiFi gear. To make a wireless bridge like this you need one Access Point and one Client, both set to Bridge Mode. The hacker's choice is the Linksys WRT54G with DD-WRT firmware.

I recently did an installation of a pair of Ubiquiti Networks NanoStation 5 LoCo devices. We have unobstructed line-of-sight for about 240 feet, so we set the power down to 10 dBi and may go lower. These units have only an Ethernet jack (and come with a 12V power injector) and a weatherproof enclosure and a web-based configuration interface. Each has an IP address to get to the configuration tool. Both are set to Bridge Mode, and the upland one is configured as an Access Point, the downland one is a Client.

I used 5 GHz because the 2.5 GHz spectrum in the neighborhood is saturated by personal networks and the community WiFi towers.

The rest of the hardware in the system is commodity Linksys WRT54G routers with DD-WRT firmware, and those have a script that reboots them at 4 AM every day to prevent "lockups" that we've seen in the past. The Ubiquiti devices, which are the trunk connection for the network, have been running continuously since installation two weeks ago with no reboots or adjustments.

Oh yeah, I use Plain Tree "free space optics", which is a laser or LED that functions like a wireless fiber cable. It's not a cheap solution, though.