designing long digital matrix

[rishi254]

Hello Sir

I have a project to log the keypresses from an hall of 60m X 50m area. There are around 500 switches in this area(actually there r 500 users sitting in this hall, each table has one toggle switch,reset switch).

Tables are arranged as 10cols X 50 rows.

I was thinking for a simple matrix logic as its extremely simple and would be cost effective in terms of cabling costs as well as other hardware required.

I have a requirement of running 60 m cables with ttl signals.Is it possible with using BUS Buffers/transreceivers?

ON the computer end i will use 60 bit digital I/O board and write the software which will scan rows and columns continuosly.

Will be feasible or there is any better alternative...

Please , can u suggest me on this.

Thanks alot
Best Regards
Rishi Bhanot

 

[Vicent Yang]

Its better to make a distruibted system. You will to put a MCU near part of the switches and scan this switches and communicate with the different avilable MCUs by RS485.