Sending raw print commands to Zebra from Windows 10 IoT on RPi3 - windows

Question

I am trying to setup a simple app where my Raspberry Pi 3 can send a raw print command to a Zebra printer over USB.
I have a working WPF c# app that will run on my desktop using the RawPrinterHelper class similar to: https://support.microsoft.com/en-us/kb/322091, but the winspool.Drv won't work on the Pi3 because of the ARM processor (from what I understand).
Seeing as Windows 10 IoT requires UWP apps, I am trying to re-write the app in UWP. I have the app working, but can't figure out how to send the raw commands over USB without the winspool.Drv from the RawPrinterHelper class.
I have also tried sending over Bluetooth as described here: Windows IoT - Zebra Bluetooth Printer
but can't seem to open a connection to my paired device as var devices = await DeviceInformation.FindAllAsync(RfcommDeviceService.GetDeviceSelector(RfcommServiceId.SerialPort)); doesn't return any devices. Here is my code:
private async void PrintAsync()
{
textBox.Text = "Searching for devices";
var devices = await DeviceInformation.FindAllAsync(RfcommDeviceService.GetDeviceSelector(RfcommServiceId.SerialPort));
if(devices.Count() == 0)
{
textBox.Text = "No devices found";
return;
}
textBox.Text = "Number of paired devices found: " + devices.Count();
var service = await RfcommDeviceService.FromIdAsync("DepotPrinter");
var socket = new StreamSocket();
await socket.ConnectAsync(service.ConnectionHostName, service.ConnectionServiceName);
var writer = new DataWriter(socket.OutputStream);
var command = "^XA"
+ "^FO20,175^A0N,40,25^FD" + "Yo." + "^FS"
+ "^FO20,250^A0N,40,25^FD" + "IT WORKED!" + "^FS"
+ "^XZ";
writer.WriteString(command);
await writer.StoreAsync();
}
I would be willing to run my app on mono and Raspbian if it can work.
Any help or direction would be appreciated!
Thanks in advance!
UPDATE: I am using the on-board bluetooth of the RP3 and not a dongle.