In the past, I've multiplexed the serial port on a micro which only had 1 serial port. This can only be done if the input data comes in in bursts with a sufficient gap between bursts to process the data, switch ports and output data, before switching back to the input port. You need 1 extra line to switch between ports and an extra chip as the multiplexer. IIRC I used a 74LS125 for this. I'm sure there are lots of better ways. Joe ----- Original Message ----- From: "Mike Montgomery" To: Sent: Friday, February 22, 2002 5:40 PM Subject: NMEA-0183 Hi all Can any one help? What I need is a project/program that take two NMEA-0183 inputs & one output ( very similar to rs-232 ) the operate on the input as below 1.It must look for a particular string & change it & output 2.if a string is received on one stream then output it but ignore that string on the other stream for a period of time 3. if none of the above then just output it What chip would be best to use have any of the chips got two rs-232 input & one or more out? mike ps sorry if this the wrong place to ask or has been ask before I am new to this list -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu