RX not responding at moderate distance (SOLVED)

Hello,

I have an RFID reader attached to my adruino with 4pair cat5 cable. usng only 2 pair. blue = 5v, wblue = enable, orange = sout, worange = gnd. the Reader doesnt seem to be sending data when i connect it to the end of the cable (about 50ft) but works fine when i plug directly into th arduino or a breadboard. same settings same code same wireing... the variable seems to be the dstnce. is 50ft really that far???

any input would be greatly appreciated. thank you.

PS. Im using the RX2 port on a mega.

is 50ft really that far???

Yes, it is.

The type of RFID reader, and how it is connect to the Arduino is important to determine ways to allow the RFID reader to be placed that far away. The color of the insulation around the wire has nothing to do with the distance that electrons can travel through the wire without significant degradation of the signal.

Why not put the Arduino closer to the RFID reader?

You should get a buffer/driver chip that can drive the wire harder than the sensor seems to be able to. There are (many) chips specifically for this purpose. You may also want to use a comparator/booster chip, like a LM317, on the receiving end to condition the receipt. You may need to repeat this going the other way, too, if you need to talk to the sensor at the other end of the wire.
Another thing to try is simply to run a slower baud rate, if possible. Slower baud rates (< 9600 baud) tend to work better over marginal connections.

PaulS:
The type of RFID reader, and how it is connect to the Arduino is important to determine ways to allow the RFID reader to be placed that far away.

I am Using the Parralx RFID Reader NOT reader Writer. and it is simply connected via the RX on the Arduino mega and a power, enable, ad ground pins. Enable is PIN 31. Power is coming from PIN 33 set to HIGH at all times and ground is grounded on an arduino ground pin.

Yes, it is.

As a profession i install telecommunications equipment. Hence the Cat5 cable and it transmits data THOUSANDS of feet through phone systems so i didnt think ~50 ft was to bad. apparently the arduino cant handle that.

Why not put the Arduino closer to the RFID reader?

because it is attached to a keypad and electric strike on the opposite side of the garageā€¦ Cant move it. so i ran cable to the RDIF reader outdie the Main garage door.

You have "sout" and GND sharing a twisted pair. That's how I would've, too. 9600bps isn't pushing the envelope, but the RFID only does 5V/0V; it isn't sending RS-232 (EIA-232, et al.)

As you're a pro telecomms installer, have you gone at it with a DVM ? You're getting the RFID status LEDs and all that stuff, good 5V at the RFID?, "Sout" is at acceptable levels on the arduino side?

Problem Solved When i changed the power to the RFID reader From a HIGH pin to the actual 5V out on the Mega.

__dont understand the reason for this but it works now....

__THank you for everyones help!!

-RKN

rkn2008: Problem Solved When i changed the power to the RFID reader From a HIGH pin to the actual 5V out on the Mega. __dont understand the reason for this but it works now...

You were trying to power the RFID Reader with/from an I/O? No way! Unacceptable.

dont understand the reason for this

The reason is that a logic output pin from an arduino (or virtually any other logic output) is not 5V once you start drawing current from it. At 20mA draw the output will only be 4.2V (according to the data sheet). At 40mA draw you start to damage the chip. Do you know the current draw of your reader?

You were trying to power the RFID Reader with/from an I/O? No way! Unacceptable.

this setup worked fine on the breadboard proto so i didnt think it would be a problem in the real life setup.

and the reader states it can work 4.5v to 5.5v so 5 volts from the HIGH with some voltage drop wouldnt go under 4.5 but i guess it does with a lenght of 50ft.

Grumpy_Mike:
Do you know the current draw of your reader?

so 5 volts from the HIGH with some voltage drop wouldnt go under 4.5

Why not? The data sheet says it will as I pointed out in the last post.

current draw 10mA in idle 90mA in active.

and yes i understand what the datasheet states. my point was it ll worked on the breadboard... the only difference in real life was the lenght of the wire.