If I use a Ethernet cable on the data pins, what is the maximum length of wire i could use? Anyone have ideas or guesses?
Jon
If I use a Ethernet cable on the data pins, what is the maximum length of wire i could use? Anyone have ideas or guesses?
Jon
That really depends on the data rate you wish to use. If your wiring a simple switch input or LED output then you could probably have it go several hundred feet if not more. If however you wished to send serial data then you might have problems after 50ft depending on the baud rate being used. There are driver/reciever chips (used for RS-485 type communications) that can send and receive data for thousands of feet with simple twisted pair wire.
Lefty
Not quite an answer, but usually you're going to use a ttl line driver or transceiver if you plan on any distance...
Prevents damage to the microprocessor and provides the current necessary to achieve any distance.
Driver pushes data out to another device, transceiver is bi-directional.
http://www.fairchildsemi.com/ds/MM/MM74HC244.pdf
http://www.fairchildsemi.com/ds/MM/MM74HC245A.pdf
That really depends on the data rate you wish to use. If your wiring a simple switch input or LED output then you could probably have it go several hundred feet if not more. If however you wished to send serial data then you might have problems after 50ft depending on the baud rate being used. There are driver/reciever chips (used for RS-485 type communications) that can send and receive data for thousands of feet with simple twisted pair wire.
Lefty
Yes it would be for serial data, specifically I would like to put a RFID reader using the Wiegand26 protocol (I think the baud rate is 9600) in one location and the arduino in a different location using ethernet wire
I was planning on using 2 wires for serial com and 2 wires to inject the power to the reader
Jon
I've seen 9600 baud RS-232 work up to 150 feet, usually, you want to keep the run a bit shorter as electrical interference starts to creep in and degrade your signal. Keep in mind that a computer port has a transceiver output to do this, you're not using a bare 0-5v TTL signal for this distance.
It would be better with shielded cable but yeah 150 feet is probably a bit long for that application. I have run some things about double that but it wasn't quite so important (I wasn't bothered about a bit of interference or losing a bit)
Mowcius
I have Arduino serial at 9600 running over 50 metres of unshielded cat 5 without issue. I do send a checksum along with the data and ignore it if the checksum doesn't match when received.