[EMAIL PROTECTED] wrote: > On your RS-485 question, i think that the generic RS-232 stuff should work > just fine for it, as is using the same UART as a high speed RS-232 uses. > The difference between the two types is in that RS-232 allows only one > device, whereas RS-485 allows up to 32 devices on a single pair of wires > (although you can use repeaters to extend this). On a project i am > currently working on, i am going to be using some RS-485 adaptors that > plug into the RS-232 port on a PC's motherboard to talk to sensors inside > a solar racing vehicle for real time telemetry. > I think that the standard functions in the rt_com package will work just > fine to communicate with such an adpator, since it does use the same UART > as a good RS-232 card does. > > Good luck. > > ----------------------******------------------- > Steve Ball > NMT EE Department System and Network Admistrator > C/S 3392 > Socorro, NM 87801 > [EMAIL PROTECTED] http://www.ee.nmt.edu/~hamster > Work: (505) 835-5330 (Digital Lab) > Shop: (505) 835-5923 (Solar Racing Shop) > New Mexico Tech Psycho Caver Extraordinaire (http://www.nmt.edu/~nmtcaver) > > The secret of flying is simple: Throw yourself at the ground and miss. > ----------------------******----------------- A couple of comments in addition to Steve's above: Note that RS-485 is a half-duplex communication scheme. A single pair of conductors is used to transmit and receive data. Most 232 to 485 adapters I've come across use the RTS signal to indicate when to activate the transmitter to go online. Now we're into some timing issues, such as getting on and off the 'bus' and avoiding collisions with other devices that wish to transmit. Also, depending on the adapter, it may or may not loop back the TXD line to RXD while transmitting. Don't forget your line terminations, either, particularly if the length of the 485 bus is of any significance (more than 50 feet? Max length is dependent on cable and capabilities of the electronics in your adapters.) The nice thing about 485 is that it's so simple, and most devices work out to 230Kbaud with no problems. //Jeff Sutherland Applications Engineering Manager Paul Davis Automation, Inc.
On your RS-485 question, i think that the generic RS-232 stuff should work just fine for it, as is using the same UART as a high speed RS-232 uses. The difference between the two types is in that RS-232 allows only one device, whereas RS-485 allows up to 32 devices on a single pair of wires (although you can use repeaters to extend this). On a project i am currently working on, i am going to be using some RS-485 adaptors that plug into the RS-232 port on a PC's motherboard to talk to sensors inside a solar racing vehicle for real time telemetry. I think that the standard functions in the rt_com package will work just fine to communicate with such an adpator, since it does use the same UART as a good RS-232 card does. Good luck. ----------------------******------------------- Steve Ball NMT EE Department System and Network Admistrator C/S 3392 Socorro, NM 87801 [EMAIL PROTECTED] http://www.ee.nmt.edu/~hamster Work: (505) 835-5330 (Digital Lab) Shop: (505) 835-5923 (Solar Racing Shop) New Mexico Tech Psycho Caver Extraordinaire (http://www.nmt.edu/~nmtcaver) The secret of flying is simple: Throw yourself at the ground and miss. ----------------------******------------------- --- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] ---- For more information on Real-Time Linux see: http://www.rtlinux.org/~rtlinux/
