Pass LED programmer signal thru Arduino

Other Hardware LEDs and Multiplexing
1

hello everybody, my name is Flo and I need help/Ideas :slight_smile:

Brace yourselves! this might be boring :slight_smile:

I've built a double sided LED display 32x32 each side using LED pixels with ic 1903. to display effects and animations on it I use a LED Programmer (either T-1000 or T-4000).So far so good
I want from time to time, to stop the animation from running, and display sensor data(like time, date, temperature, pressure etc). And for this I'm using Arduino Mega 2560.
The display works well with the Arduino, and it also works well with the T-4000 programmer.
Is there a way to control the data flow from the LED Programmer using the Arduino?
I've tried to pass the signal from the T-4000 using Serial1.
I've tried to determine the baud rate using this code: (found here: Auto serial baudrate detector/selector - Development - Arduino Forum) I've got 115200

int recPin = 19; //the pin receiving the serial input data
long baudRate; // global in case useful elsewhere in a sketch

void setup()
{
pinMode(recPin, INPUT); // make sure serial in is a input pin
digitalWrite (recPin, HIGH); // pull up enabled just for noise protection

Serial.begin(9600);

}

void loop()
{
baudRate = detRate(recPin); // Function finds a standard baudrate of either
// 1200,2400,4800,9600,14400,19200,28800,38400,57600,115200
// by having sending circuit send "U" characters.
// Returns 0 if none or under 1200 baud
Serial.print("Detected baudrate at ");
Serial.println(baudRate);
delay(300);
}

long detRate(int recpin) // function to return valid received baud rate
// Note that the serial monitor has no 600 baud option and 300 baud
// doesn't seem to work with version 22 hardware serial library
{
while(digitalRead(recpin) == 1){} // wait for low bit to start
long baud;
long rate = pulseIn(recpin,LOW); // measure zero bit width from character 'U'
if (rate < 12)
baud = 115200;
else if (rate < 20)
baud = 57600;
else if (rate < 29)
baud = 38400;
else if (rate < 40)
baud = 28800;
else if (rate < 60)
baud = 19200;
else if (rate < 80)
baud = 14400;
else if (rate < 150)
baud = 9600;
else if (rate < 300)
baud = 4800;
else if (rate < 600)
baud = 2400;
else if (rate < 1200)
baud = 1200;
else
baud = 0;
return baud;
}

And I tried this out : (data line from T-4000 connected to RX1 pin (pin19)on the Mega and data line to LED panel to TX1(pin18), and of course common ground)

and simple code:

void setup()
{
Serial1.begin(115200);
}
void loop ()
{
Serial1.write(Serial1.read());
}

Well nothing happens (except the first two LEDs that light up quite random)

Do you have any Ideas? maybe some external circuitry proposals? (I've tried to control the signal with a BD139 transistor without any real results(my bad ). I won't post the circuit diagram as it might make you laugh! :slight_smile: )