Hello Pete,I designed a 3rd party IRLP board a few years ago, and published the designs on my web site:http://www.qsl.net/k0kn/plri.htmlI am using two of these on app_rpt with good results. The hardware DTMF decoder is not supported by app_rpt however.I'm not sure how app_rpt would handle using one parallel port for multiple nodes though. I've not tried to define parallel port pins for more than one node on a server. My parallel port definitions from usbradio.conf:; IRLP board supportpp3 = ptt ; out0, out1 or ptt; pp10 = in ; in, cor or ctcss; pp12 = in ; pins 10,12,13,15 are for DTMF; pp13 = in ; pp15 = in pp11 = cor; pp4 = out0 ; pins 4,5,6 are AUX 1,2,3, default off; pp5 = out0 ; pp6 = out0 73..KyleK0KN--- Original Message ---Hi All, Is there a circuit board design for running COS/PTT for multiple radios off the parallel port? It would make using consumer FOBs much simpler. It would need some PTT drivers and COS buffers. I thought there might be a cactus board or 3rd party IRLP board that may already in circulation. Pete