--=====================_970334467==_ Content-Type: text/plain; charset="us-ascii" Scott Dattalo wrote: >On Fri, 29 Sep 2000, Paolo Mortillaro wrote: > >> Does someone known some link's referring to send communication and supply >> on the some two wires ? > >No, but there should be! I've thought about doing this and it shouldn't be too >hard. However, you would have to trade off cable costs for node costs and in >most situations the choice is clear. > >I don't have time to draw (pretty) ASCII art, but I think I can describe it >clear enough. Imagine the power and the communication link as two signals. The >power signal is "low frequency" while the communication is "high frequency". If >two signals occupy different frequency bands then it's easy to mix them and >separate them out. In this case, a low-pass filter would couple the >low-frequency or power to the cable, while a high pass filter would couple the >high frequency or communication link to the cable. ......... > For a simple "power + RS232_xmit" scheme on the same wire, the following might work. RS232 voltage idles at -12v between characters. Use an LM1488 TTL-to-RS232 line driver to invert it to +12v. Typical LM1488 gates have 300 ohm output resistance, and short ckt drive of 10 mA. Half-wave rectify the +12v at the remote end, and run this into a low-power 5v v.reg to drive the PIC [it is a PIC - right?]. Now the same line can be used to send characters, just so long as the line isn't held low for so long that the cap in the half-wave rectifier discharges. Note that this scheme adds an "extra" inverter into the Tx line, in addition to the one in the PC port. Since there are 4 gates in the LM1488 chip, each with a 300 ohm series output resistor, you could probably parallel all four gates to drive the line. RS232_rcve is handled by a PNP inverter, using another part of the LM1488 to derive the idle -12v. See attachment: 2-way.gif - Dan Michaels PS - If anyone tries this scheme and it actually works, I'd like to hear about it. --=====================_970334467==_ Content-Type: image/gif; name="2-WIRE.GIF"; x-mac-type="47494666"; x-mac-creator="4A565752" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="2-WIRE.GIF" R0lGODdhQAJAAYAAAAAAAP///ywAAAAAQAJAAQAC/oyPqcvtD6OctNqLs968+w+G4kiW5omm6sq2 7gvH8kzX9o3n+s73/g8MCofEovGITCqXzKbzCY1Kp9Sq9YrNarfcrvcLDovH5LL5jE6r1+y2+w2P y+f0uv2Oz+v3/L7/DxgoOEhYaHiImKi4yNjo+AgZKTlJWWl5iZmpuSkEAGDgCfoZEEo6Wop6qirK atqKyhkrizc6a3uL21Cr4LlrWipa65tb19sbbEyaIAxsfOwMTMwzDHogjHBqXS195/tJ3Zy9rU0u Ta0DvqzMq37O/ea93q78rV4uT+yOk46Nf0//zg40ZP3W1Ss47pe+gDT4aQM3cCHDNNcS/jt4b5fE /okzzlXEh7HaRo5lNFq0KM6fSW4jOw4MtuyYSoUySVJsF9HeL3bWXs5qaTOoUDnQiho9ihTo0CpJ mzp9qnSp1KlUKUStijXrhqtau3r9Cjas2LFk95U9i1Zn2rVs27p9CzduPrl0pXKti1eNT4V52UbD FQ9k37V3I8UrXAHx4EXeks1k8K2mM5TIsjkW81LxBM2LEa18iHNytJAA+x3+DMZhZ8IIRaqNaXqe 6cn+yHhsvTos6tIp2Tk+vI30yTHuLo/gnHtQTZo9XemCfDlUOJnI/VRPLuv60FSvVjnn/t07+PHi y3c/Hx49efXisbt3oD1O/Pd0fNLWFT3/csj0/vtrAY4bbqQN+MB8/h1oA4AXqPaPBwa68WBVgS0Q 2XQWRtiEfb9p+NdyxoGA4Roh2vUaNiYpOBwaH/HEX4EptojgJiuyaOJvJd5EzoQ0XlSbizFyMuBu Ke4loj33UZjZhkd+MCKO9QkIW2U97dckBsOMBt1+DWZV5RldMjEaagdpFFI4XSxJEVRqrvlXgCW0 +SONGFWUUj3XCBknCU1GlieMBgWXI6Di4NlnDVcxQ8V9in7oJ1EI2ZnTnfIQWmhHC0b5BIrSmQjB l2C21qZ3IolZqQl7IsnUpKWtap2NATIjmX5wlsrBqdBBQZ2ggNKK4KEFemrqqnZueSOvcfna/imw HZw2m5vFGivhCi3NCsSisWoJbVq2bqZstt46eKkF1J5ZSHFJsIkuo1yGu2C3CZZ7GxLbUlLUYz1q YC6+2qH5Fbbu4iutJhNS2u5ztSKnI1iM/pvBvJZceW9iBlPIZHwMTyzIkhezi8LGXlK8LMbPWqmZ umYRspfHEqugckm+jcwxzCQDrK195wacycDONiwyiFeOi7CPPTNi1IvV4ozJbohB5O8JzRBL07jw RSwcaFNDaDJ+9SKcNYhIe4Ws0x0GO9yM4+jTcg78wodUxdiK4HA+6ab7ddRzFw1l3lPezfdT7HXX d+CCD074UdIWnnaides5NtIOJS5v10ga/u6g5OCyHALkZoTNeDlfVu2aVfBYHtPWbkt9eQrXae6y uG/+DOxCUbH+rrj1Rmzl4m9mzpjuB7t1qM1eY048k70XXzlcwRu3uu/H8Z5dzPp6Qbuh7VIJverO 5x69679/UX1D10M8vPbIh6xI3ImFL8nyIBt/PtnwJ6K+BKj7VfD7qXe8vfQ5+5+szckHgLjTGpuy x7/yAYmAt/oYHNiXQPPNbwv3UwnpZDbBX+Whgo15G6fU5kAJ7i8L01LaykSIHz3E64OU6RQIBRi/ rXBBKWiz1wjtp8E2SCRfIyMQBvsHA8rtLoY0+w8vUnZEWOyMeyc84gNdWDrmJbE3tfGY/hUlszc9 AbGJWKDhjcy2RAQ2xzpDS9jZ9Cc+Q4UqiXDbouhm+MYXgQ5qbWThH1YIqucwKI0uadQYMyi/G3Zx h0qS4vO855wnRQB1tLndSSrIAtbV75CA/J/rIOkkCP1gknWsJMoOR6uNWAtoRBJaxxDXNgUeAoJ9 2aFsoFYYSVovhO/jYCwfwcogIjI2vGTiNGY5QDruKI5EC2aywqTEh3jwaj1gWC5fx0wL+uuZdREl GmdySx84U0VRxBKPMCXGFg4JVheqkcKg+EVOZbOZwGydOEHCL6640omtSCQvUfQnow2Bmi0gpGiS tKl1/pKP7rQhwQoYTT8CpEw8oSKB/sxoBH5GcpMUJShmZDWdGoVJnzxraEJ0JqWQQnQqstRmO1ep xR2JKSe9HNXaSGTSmFqqewl9Z77w6UMlSNSNYkPX4XxKxEv4MxmBiefeyOnQTz2RJDslQlPf8lTb HO9bQ0yQ34J41YnStJhL5UhUU+WIrwaSIWKtKFVTqja8qdGRLiirTM/ayYm4NQpzPVpX5foTXBpz B8t0yb/qytf8rSc9hB2sYc1TWMQe9m+JZSxgVRmQx74QrnElK2W9ahPJXvYKmiXhVDcrSJZ8FrS1 yixp39HZLp5WtOAz5TVlkNqTrtaXFKSabTcWW4vOloGKK9uWwPiC3O52CagsLuFe/pOwDqo1gsNt 7qNqSUynbY55fU2nczd4Wy6ONTVGCqObhHvdcP7Qu54k1zDp8TbwhjeiPOWsq8Cpiguu1zDtrS2s sGnd+dKrvr0NlNX+61v97jeoZ6LuM4z00ojKV8DsJDBhFsxgGWo0qa7dLryMi+EMa3jDGXZsfDmc ykGCiqHoZC5KFVzdtsT2M8PiqItDq2IIn2XFBbFMil8cMojukaSrofF/54RDzOn4tWzgp3pVWNs/ ssqaQs4veWF4hCNjd5DXSiZHbfURgN4Ys52RMozrSKdX4hivXd7DtoDcUoTSsghe7oaZv6bcVMg4 DEbu8ZsdrDC6kWVue5VuhP/M/lvIlgvQkOBkIMIHlRg7RZEoJLSjh4bWR0uayJT0DJuXC1VMOwrP d5z0aC3s6eQkuNHHmXO/MImWLd9g1CZmnKqnHOpSg3jWtOazpWNd6eCaurw+e/V03ztmXAe6p6iu rKuLXdB8qlnYRYStbKsqEJ3klNlf5m+uQS0fjZ2X2h2dqbdbPYcZzZHbpdVtcK0NZVUFm9xB/nYM DK3JNAPXzLt+2LPbim43Z6zeldimuSO9yloLfOAE37CHKyO4fAsa37YD8WlZrW9Sn9vd7Qb3Xe/I 7yIrXLxa1S60wz3oT3J64xL2OMA322ZsG/vdFF8kyX+U8o+rvOMs36WfixFy/uW8vNwia+R4hanQ k/cZEDEXutFpjqqMkNjkFZb5ZYt+bacj3U+SmnfTS3xz0kJ95UeXuJwE5WugU5rr8Mh5xnbe7WgC 2epsA6rX4312s2ddl6bE0kEXHvWzxhJtLBX7zUY+9wkf9Z1WYbXsRkmmNYL2lkBZen8tznCLys61 JvwmzuPuvcar2wrwRnuzWbX5RpGqpkMn4wmnRRDVAv7tLFNURn71oYNuvd+Fh3iWVc/6qU9cmjCr oTBnT3uOwWn0YM396gN5+98ntPKXl3vFh6+3KXQe8pEPneeufqSFRdz5fJj+zM1KfbgCH33G/z74 A49ykZe/653wfJJ1rv7w/sv//ObXS/wxP3/079P97xk/3smue+13fIXif//HcdXnVPznWfgHf+uX f5P1gNzUgBOof3SXgANYKgXIcxFYgW/VgXp3f/XHgaumgN+zWI2FgicoSRKlgWlXgd6HDiU4CXwi LwyofzAIgR8YWUomgIfWT2Kmgw3mgLnQGPtHgRK0KRhYO0MIGEnngUR3bgemhPeWd1zmhDHIfaoj hUxIglO4VVe4hCGohVs4gl3IhbYgSrh1a5EkGkA0eaRHfmWIhtwShkdIbGT4Oh40R3u4bEwHgJZV eFTYB38VImsDRofod9ElgnNhO/82iGtVcI1jeSiBODLYPg3TLS34ebo2/oYc9FuJ6IKLKFTqsjT7 kjUj4YmCl0NKxXKFKF98uDySg4PB1yAlEzTOwmSLxHxwyGbO1oe7F3SbUXFBaEn1BIqr+Hl4FIzL OG3rhoW752XMN4v9hoe/qIsHo4dYZzevkiuvwoo/eIx0JW1PFofFUErxYzF3MVLzJIzf9YnEBYzW KI6l83Mlt1fuA0gGEipAUyy56HKw1CNP9TnbZkTPFY6hCHcBqRZsB3vQZyrJlyXUgopD9WEeQk/f SGrRqDfTSD0R4XMGeZDD6Gr1SJDdF4CaKI8IqUNXsyJxVonnEzhZWIUoyZHcZXnNqI9jSJKfJnUg 54W2EXvQ1ZPJc0ax/lCTvjh4NmSAS3loyKaIFcNGXyiKajRigsF+TMlamYOSQiiH31Z1ISmSQwmI UGmFXYmU+VQhEXKURkmWTGWJ0LZ2YPmPZ5hX3xMUa2mB9uR4B/iHOzg9S4GX/YRRhMdrfDmWjchj RJQZoRF2OvWWhZY/VEFroqeXSslZj6lXgRhK8yAp5JghmBlWdGgsi/kn58h5oNkIaegtjwN65kWX UglO0KIaSWiTr8mWDURVDDJuuGeWtxmb7AaPP7lAdgScnymcMsKDxWmctrlATqmc9CeWkbWVzTWZ z1mc02mdupGd2xmW3Omdcvmdwoad4YkV4/l4k+gRSJWUEEeefdkV/hDxR9CXVJrSnuCYahTTYo+0 KwAGeubpHv4pBfzQGyDFHCK1k/XZdgcENmi0Um0ob5aJoJWimzszn2IGoBFKC30XHKSYlAXKnhi6 PosGoiNKoiVqorMlRCeqoivKoi3aJ43pojEqozNKozVqozeKozmqozvKoz3qoz8KpEEqpENKpEVq pEeKpEmqpEvKpE3qpE8KpVEqpVNKpVVqpSAqkZ6JgO3oQhd6pcrXg1rkpV/Kjh1iI4MZUh7KF5SW lnbUptv4pdt3VMTnpvjljt5kmpWpdM81pldKPq+nikzTjTnioMiVQoBKGWwVp4xmU1OzY1Fjp4bK H0F5kym5qF6SqnjUgabpmV4Idy95yqlWpip9eqm6BqNzWaqpqqqrmp0TSizllKb2xKp36YRm8jKR SpizOoNnukzpkJ9VtJ/Wp5+6SoujQqEgM6DjmKZGRawDxp88FH2ZiofNaKnNCoUPqlA6clNAOFLW mprARjUaahAcuqzU5a3niq7pqq7ryq7t6q7vCq/xKq/zSq/1aq/3iq/5qq/7yq/96q//CrABK7AD S7AFa7C5UQAAADs= --=====================_970334467==_ Content-Type: text/plain; charset="us-ascii" --=====================_970334467==_-- -- 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