IP adressing VS Serial

Hello
I'm wondering if some of you have figured out a solution over ethernet connection for small application with multiple local panel using the same program....

Previously with serial communication we just had to connect the cable between plc and hmi and all setup could run on the same node adress...(PLC = node 0 HMI = node 1)
This way, even if you have 10 unit on the same plant, you could use 1 spare plc that could replace any of them and the same for hmi...

But now with Ethernet device, everything is connected thru 1 ethernet network so the same 10 plc with 10 hmi need an unique adress for each.
If we have to replace 1 unit, we need to program is ip adress to fit the broken one...Or if we sell a new unit, we need to ask for a free ip adress...

Is there any easy option to made this easier...

This solution may work for you.

http://www.plctalk.net/qanda/showthread.php?t=55472

You would need to ensure that all of your spares are setup for DHCP.

Shawn

With some HMI's, it is possible to automate the process of assigning the IP address, making it part of the boot up process for your spare. I have a G3 that can do that. I did give it an "out of the box" address that is reserved for it as a spare, in case we want to do a download over ethernet, should something go wrong with the clone card at the machine.

The technician is prompted to select (from a list of buttons) the machine name when it is powered up (or programmed) for the 1st time under normal conditions.