How to connect Two PLC's at remote sites ?

[mark30504 0]

Hello We are looking for a way to connect two AB plc's together to pass data. Each is at a different site. To far to wire or radio modem. Considering serial dail up modem, DSL, or anything else that might work. Ex. PLC 1 would be programmed to call PLC 2 every 10 minutes. PLC 1 would collect date N7 stuff and set a few bits and hang up AB's modem is call a Dial IN modem, AB site seems to have no ideas thanks for any suggestions Mark30504@yahoo.com

[Nathan 7]

Do they both have Internet access? Setting up a permanent VPN tunnel may be a viable option. Then each device could see the other as if it were local. My experience with AB modems were that they were: expensive, complicated, and didn't work well (an understatement). May be better now, but I wouldn't recommend them. I was successful with a project about 6 years ago that used phone gateways on each end to automatically establish an Ethernet connection. The 3COM devices were cheap and really easy to set up, but they were "home" devices primarily for sharing a 56k modem with a small home network. In that particular case the (commercial) phone bill to the customer ended up being outrageous.

[BobLfoot 302]

If each site already has ethernet and internet connectivity then a permanent VPN tunnel is the most secure and most efficient method. If some other issue makes hooking to existing ethernet impractical then DSL or modem becomes a possible solution. DSL would still need a VPN unit to be secure and safe. As for modems I'd use a either US robotics {AB site has isntructions on this if you dig a little} or a cheap $299 local PC with RAS setup and let the PC's do the dialing and just ethernet PC to PLC at each site. Saw a post on mrplc last week about doing just this.