RS485 3x4 Keypad

Hello.
I have this project for one of my customers where I need to have a keypad (0-9), '*' and '#' and be able to address via RS485 connected
to the computer. The user will enter a number in the keypad and when they hit the "Enter/#" key it will send the code to the RS485 port. I need something like they have at http://www.aaaremotes.com/ekp485ellike.html . That is my perfect unit, except that there is no documentation for that unit and looks like it only works with their controller box. I have thought of connecting a data sniffer to the unit but it probably wont work without getting their main unit/controller which is like $6K and I dont want to but it just to figure out how their keypad works..
Can anybody point me in the right direction? I dont come to the newsgroup alot so it would be great if you could also e-mail it to me at snipped-for-privacy@optonline.net.
Thanks Mike
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Think you can find exact thing you need by going to Keyboard MFG, but will be OEM items. If only need 1, go for a sample.
http://www.google.com/search?hl=en&ie=UTF-8&q=RS485+keypad&btnG=Google+Search
If using a PLC or microprocessor could use 3 outputs and 4 inputs to form a row / column scan matrix to detect key inputs and a RS485 display they detected inputs. Parts LOW COST at DigaKey.
Also could do with a PIC microprocessor w/ above and RS485 output to customers RS485?

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If You want to do it in a PLC, Use a Direct Logic DL06, It has enought I/o to scan the keypad, and a built in 422 port. ASCII in / out, the program package the whole thing would cost $500 including enclosure. Total programming time about 1 hr to write the ladder code (add 2 hours if it's your first time with lader logic)
Rex Karz
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