Stratologger CF and Arduino Mega

[nmrs.thrust]

Hey everyone. I'm trying to have my Stratologger CF communicate with my Arduino Mega 2560 using RX and TX. The manual gives little information on the subject. Has anyone attempted this before? Because I cannot get it to work. Here's my wiring and code...

So I am connecting GND to Arduino ground, TX to Arduino RX1 and 3.3V to Arduino 3.3V power. Here's the code I'm using:
void setup() {
// initialize both serial ports:
Serial.begin(9600);
Serial1.begin(9600);
}

void loop() //read from port 1, echo Serial monitor:

{
if (Serial1.available()) {
char inByte = Serial1.read();
Serial.print(inByte);
}
}
But half the time, the serial port doesn't read anything or it just spits out question marks and random numbers that are definitely wrong. If you have experience with this, please help me out. All the serial research I've been doing isn't helping and I'm just stuck. Thank you!

 

[Voyager1]

I have no problems reading the telemetry from my SLCF into an Arduino Mega with your code. I am powering the SLCF from a 2S LiPo, not from the 3.3V on the data cable. The manual does say not to apply any external voltage to these pins!

 

[nmrs.thrust]

I have no problems reading the telemetry from my SLCF into an Arduino Mega with your code. I am powering the SLCF from a 2S LiPo, not from the 3.3V on the data cable. The manual does say not to apply any external voltage to these pins!

I am powering it with a 9V. The reason I connected the 3.3V is because I read an article where they did that with a Raspberry Pi. Could you share your wiring with me?

 

[Voyager1]

Same as above, but no 3.3V.
SLCF GND (Pin 5, Brown) to Arduino GND , SLCF TX (Pin 4, Blue) to Arduino RX1.