Epson TM-T88III via /dev/ttyUSB0

Last week I got a new Epson TM-T20II to work with node-thermal-printer over an ethernet connection. It really does work great.

But now I have an older device, an Epson TM-T88III with a serial-port connection. I’m ussing a serial-port-to-usb device to connect it to my computer, so I’m trying to connect to /dev/ttyUSB0 like this:

let printer = new ThermalPrinter({
	type: PrinterTypes.EPSON,
	interface: '/dev/ttyUSB0',
});

// This is always true, even when the printer is off. I think it only tests if the /dev/ttyUSB0 file exists?
let isConnected = await printer.isPrinterConnected();

printer.alignCenter();
printer.println("Hello world!");

printer.cut();

try {
	let execute = printer.execute()
	let result = await execute;
	console.error("Print done!", result);
} catch (error) {
	console.log("Print failed:", error);
}

The printer does absolutely nothing. This script eventually times out with this error:

Print failed: { [Error: ESPIPE: invalid seek, write] errno: -29, code: 'ESPIPE', syscall: 'write' }

I added my user to the required groups, set the correct permissions on the /dev/ttyUSB0 file and all, but still nothing happens.

I saw node-thermal-printer was tested on a TM-T88V, so I was kinda hoping it would just work with an earlier version of that. Is it too old? Or is something going wrong with the connection to the serial port somehow?

---

Edit: I added the debug option to the write-file-queue instance, and that gave some more info:

Attempting to write to file #0 @ 1563358688918
Callback from writeFile for file #0 @ 1563358689187
Error occurred for writeFile for file #0 @ 1563358689187
{ [Error: ESPIPE: invalid seek, write] errno: -29, code: 'ESPIPE', syscall: 'write' }

[skerit]

Well, unfortunately I only have an RS232 and an ethernet printer to test on, but if issue #58 is any indication it should all work the same way: just use it as a file, but with the appendFile modification.

The easiest way to test if this would work is to simply echo to the device file, like:

echo "Testing!" >> /dev/ttyUSB0

Other device files could be /dev/usb/lp0 for usb printers? Don’t know where parallel ports would go…

[stale[bot]]

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