Can you sniff RS2332 Data?

Projects General Guidance
1

I have a need to sniff the RS232 data from a weighing machine controller. The controller has an RS232 output, but this output is already being used to display the data on an external large LED display.

Can you just solder a wire the RS232 TX data to the RX pin on an arduino? while also continuing to send the data to the external led display?

In other words what will happen if I just wire it up?

RS232 External Display
+---+ +---+
| TX | ---------------| RX |
+---+ +---+

Arduino grabbing the data along the way

RS232 External Display
+---+ +---+
| TX | -------|-------| RX |
+---+ | +---+
|
+---+------+
| ARDUINO |
+----------+

I know that if the RS232 Data is real RS232 then I will need to push it through a MAX232 or similar. But we can just ignore that I think for the moment.

Or should I actually have the RS232 Route to the Arduino and then setup a second serial port on the arduino to send the data to the external display?

Chris

2

Yes you can sniff it like you said.

3

Great

Thanks for the quick response....

Chris

4

I know that if the RS232 Data is real RS232 then I will need to push it through a MAX232 or similar. But we can just ignore that I think for the moment.

How can you ignore +-12v on an Arduino pin?

Or should I actually have the RS232 Route to the Arduino and then setup a second serial port on the arduino to send the data to the external display?

No, just tap the existing wire as drawn, but see previous question.

Rob

5

How can you ignore +-12v on an Arduino pin?

I think he means he is aware that it will need dealing with but it is not the thrust of the main question he wants to know about.

6

Grumpy_Mike:

How can you ignore +-12v on an Arduino pin?

I think he means he is aware that it will need dealing with but it is not the thrust of the main question he wants to know about.

yes you are correct, I just wanted the question to be simple and to the point.

I know I need a max232 or similar.

Cheers

Chris

7

Yeah ok.

Rob

8

Really all that is needed is an NPN transistor and two resistors to convert rs232 to arduino TTL.

http://www.scienceprog.com/alternatives-of-max232-in-low-budget-projects/