ML1400 and 1762 I/O

We have an application using a ML1400 with five 1762 I/O modules attached. We've run out of space in the panel and would like to locate some I/O remotely.
One suggestion is to upgrade to a compactlogix and utilise the existing 1762 I/O if possible which would reduce cost and hastle of replacing I/O. I know this is a long shot but is it possible to communicate say over Ethernet to the 1762 I/O on their own without a processor.
Another suggestion again if possible is for ML1400 to communicate over Ethernet with remote I/O. Having done a little reading and research on both I don't think either is possible, however hope springs eternal. I would appreciate any help or pointers on this.

tgoulding said:

Another suggestion again if possible is for ML1400 to communicate over Ethernet with remote I/O.

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I recommend reading Ken's post (post#2) in this thread

tgoulding said:

I would appreciate any help or pointers on this.

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Is there any 16 point I/O that could be changed to 32 point? Or is that not feasible.

If response speed of the remote I/O is not critical, you could put another ML1100 or 1400 in the remote location and connect with Ethernet to the main PLC. Use MSG instructions to communicate between them--the program in the remote unit would be very short and would simply transfer the transmitted data to/from the input-output data files.

Thanks guys for confirming my initial thoughts.

FreeWave Technologies has wireless I/O radios that will operate with Modbus RTU. If the serial port on the ML1400 is available you can make it a Modbus RTU master and then read/write to the remote I/O points. The FreeWave radios are very robust so reliability won’t be an issue.
Find info on the radios here: http://www.freewave.com/products/product-298.html
I’ve tested these radios with ML1100’s and an SLC5/05 and it works well.

The 1762 IO is not compatible with any of the CompactLogix products.
However, whenever we run out of physical space or IO (a common problem), we simply add another 1400/1100 with more IO modules and communicate with MSG instructions over Ethernet. Performance over the Ethernet is extremely good and with careful thought & design has always been a reliable approach. Plus you end up with spare parts built into your system (works in a pinch if you thought about it in your design).