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1  Using Arduino / Networking, Protocols, and Devices / Re: Serial Communication Woes with Mega 2560 on: January 08, 2013, 10:51:14 pm
Thanks for the replies,

If I understand correctly, then the TX and RX pins can be working perfectly correctly even if I do not see the respective SM LEDs flashing? I will certainly try looking at Pin 1 with an LED + resistor in the morning.

As for the "other code" I've mentioned, I have sometimes included a pin 13 "blink" as a heartbeat to see that the board is functioning. In most cases, this blink will occur after I connect the board to the external power supply. In a few cases, the board simply held the pin 13 LED lit indefinitely, but I suspect that this problem was related to some out-of-date drivers. I thought I'd mention this in case it were relevant.

The logic analyzer sure looks appealing, and perhaps would be a useful tool to have in the lab...
2  Using Arduino / Networking, Protocols, and Devices / Re: Serial Communication Woes with Mega 2560 on: January 08, 2013, 08:03:22 pm
Thanks for the reply bilroy,

In the simple test case I've described, I haven't actually implemented any of the chain. I included a description just in case it would be helpful to know the context. With the simple sketch I've described, I've only connected the Mega to an external power supply, and left the TX/RX unconnected. Should I not expect the serial communication to initialize when the TX and RX are left unconnected?
3  Using Arduino / Networking, Protocols, and Devices / Serial Communication Woes with Mega 2560 on: January 08, 2013, 07:43:47 pm
Hello,

I am using a Mega 2560 for a nuclear physics experiment. My plan is to place the Mega at the high-voltage terminal inside of a tandem accelerator to control a gas system, and interface this Mega with LabVIEW via optical fiber links. When I run the experiment, the Mega will turn on when the charging chain inside the accelerator is activated. I will then establish serial communication with the Mega. My entire scheme is as follows:

LabVIEW ----- RS232 ---- Fiber Optic Conversion --------- RS232 ------ TTL Conversion ------ Mega

My problem here is that in bench-top testing, if I turn on the Mega under any circumstances except when I have it connected by USB to a computer running the Arduino IDE and "serial monitor," any code related to serial communication does not seem to run. I have tested the functionality with a simple sketch:

void startup()
{
     Serial.begin(9600);
}

void loop()
{
     Serial.println("Alive");
     delay(1000);
}

After uploading this sketch, I will see the appropriate message sent to the serial monitor if it is open, and see the TX light blink periodically. If I reset the Arduino without the serial monitor open, then I do not see any any blinking of the TX light. In some cases, the rest of my code will run; in others, it will not. I am hoping to find a robust solution, because the Mega will be entirely inaccessible after it has been installed in the tandem.

Thanks very much for any help,

Will
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