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hi to all i have this strange problem,i have two scenario, in first scenario i have a energy meter, i use this shield enter link description here, i can read data from energy meter. all work well. in second scenario i have a energy meter i use this RS485 shield enter link description here but i can't read the data, i don't know where is the problem in second scenario i have this configuration:

rs485 brokenout - arduino uno rev. 3 3-5V - 5V RX-I - PIN0 TX-0 - PIN1 RTS - PIN2 GND - GND

and i use a 120 ohm resistance from A and B connector of RS485, but i don't know where is the problem, can you help me?

best regards A.

Ant
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1 Answers1

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First I believe your schematic of RS485 Shield which shows 

D0(RX  input)  <- RD(pin1 output)
D1(TX output)  -> DI(pin4 input)
D2(EN output)  -> DE(pin3 input)
set Jumper B-C -> RE(pin2 input)

Noting I have added the direction of signal.

versus the Breakout RS485 where you state

D0(RX   input) -> RX-I(DI pin 4 input)
D1(TX  output) <- TX-0(RO pin 1 output)
D2(RTS output) -> /RE & DE(pins 2 & 3 inputs)
       GND     -- GND

Where the above indicates that you have TX and RX swapped between break out and shield.

Noting D0 of the UNO is RX input to the UART of ATmega328P. I see from the above that the Shield is properly sending the output of the RD into the D0(RX) input of the ATmeg328p. And should be working correctly. Where your Breakout appears to be sending the output of the RD into the D1(TX) output of the ATmega328p.

mpflaga
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  • Hi mpflaga, thx for your answer but the see the Breakout RS485 is broken, this is the problem. Regards A. – Ant Jun 25 '14 at 08:50