> We've got an RS485 comms pair, which we want to multiplex between 120 RS485 pairs. > I.e. 120 channels to 1 (or 240 to 2 in terms of actual wires). > Ive seen a 32 channel analogue switch from Analogue devices, but im unsure as to whether an Analogue switch will be ok?
You wil get yourself into a lot of problems. No multiplexer can do what modern RS485 buffers do, like 1500V (or even much more) ESD protection, short-circuit protection, over-voltage protection etc etc. And you will get impedance or reflection problems. What speed does it run on? What i wrote before is really the best solution: repeaters. Repeaters are for sale for all kind of RS485 networks. And if you want to save money, buy 4 repeaters and make 4 groups of 30 devices. Or 8 repeaters with 8 groups of 15 devices - so only 15 will stop, and the rest continues working. Pieter ______________________________________________ Hoeben Electronics Phone: +31 6 51590081 Ronkert 44 Fax: +31 13 5096025 5094 EW Lage Mierde Private: +31 13 5096200 The Netherlands E-mail: [EMAIL PROTECTED] http://www.hoeben.com ______________________________________________ -- Author: Pieter Hoeben INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
