VISA serial read / write to microcontroller issues.

[kierzie123]

I am running Windows 10 Home 64 bit and LabVIEW 32.  I am using VISA serial  to send parameters to a microcontroller (AdaFruit Itsy Bitsy M4 Express). I have worked with  serial instruments but this is the first time I have tried to write  instrument control and I am stuck. 

I do not understand why characters I write to the port come back in the read and the device response remains in the port.  I do not understand how to send ASCII "CONTROL-D" to soft reset the hardware. I tried 0x04 with no success. The communication is ASCII based and is flawless in a terminal emulator ( PuTTY).  I want my LabVIEW re-entrant VI to work that well. A screenshot of a PuTTY session is attached.

I have read and implemented several useful posts in the forum to get as far as I am.  The zip file includes details for packet and requests during sessions with my VI and PuTTY.

[crossrulz · Accepted solution]

1. A Ctrl+D (End Of Transmission) is a character value of 4 (0x4).

2. Initialize your port with the VISA Configure Serial Port.  It will then default you to having the termination character turned on, which I think you want here.

3. You should not have loops inside of loops like this.  Just a single loop should handle all of this.

4. I recommend you go watch this: VIWeek 2020/Proper way to communicate over serial.  There is a link there to code that I use on a regular basis that I think will really help you out here.

[kierzie123]

Wow! I watched the video. The techniques for ASCII will help me make the robust GUI I know is possible.

Thank you!