Arduino not receiving

Hi! I have a device which has a RS232 connector and works at a baud rate of 57600, and I use a TTL usb adapter at the end. I can communicate with it via serial terminals, like Realterm, but if I replicate the bytes I write in realtime on arduino, the device simply doesn't respond back. Why? Maybe it can be the wire too long? Wires and adapters, from arduino to the device, are long 3 mt together...

Your post title says "Arduino not receiving".
What have you done to determine that?
Have you added any debug printing to your sketch?
Have you hooked Realterm to the Arduino to see if you can communicate directly with it?
Have you included any code for us to examine (no, you haven't).
You essentially say to us "It doesn't work. Why?"

  1. What have you done to determine that?
    Because I can communicate with the device using a serial terminal, but not with Arduino

  2. Have you added any debug printing to your sketch?
    Yes: https://scontent.xx.fbcdn.net/v/t1.0-9/15589518_1664884013529165_2858923012288560175_n.jpg?oh=0e64045864e388781d2b8d8354a211fc&oe=58EE171E

  3. Have you hooked Realterm to the Arduino to see if you can communicate directly with it?
    Again, Yes.

How can we be expected to help when you have not posted your Arduino code
OR posted a link to the datasheet for the device you are using
OR posted a diagram showing how everything is connected?

...R

The sketch is linked in my second post.
This is how I connect my devices:
Device (Thermocamera) -> RS232 cable to USB -> TTL adapter -> Arduino Uno

If I do:
Device (Thermocamera) -> RS232 cable to USB -> Computer
I can send commands via terminal and get the response.
But not in Arduino.
That's the problem!

Post your program here where we can access it easily.

Post a diagram showing how each wire in the cable is connected at each end. It is quite possible that the connections are not what you think. There are different types of RS232 cable.

...R