"device or resource busy" from line.requestOutputMode

[dkossman]

This is probably something pretty basic that i missed but would appreciate some help...
I suspect something to do with the pin numbering scheme, but i tried a few variations and still can't get it to work.

I'm on a Pi Zero W running buster:
$ uname -a
Linux neonpi 6.6.74+rpt-rpi-v6 #1 Raspbian 1:6.6.74-1+rpt1 (2025-01-27) armv6l GNU/Linux

i have a relay connected to BCM pin 17, physical pin 11.
I'm able to successfully toggle this using pinctrl from the command line, and it turns the relay on/off.
e.g.

$ pinctrl set 17 pu op  # set to output with pull up
$ pinctrl set 17 dh # drive high
$ pinctrl set 17 dl # drive low

However the node program below yields

1.6.3
/home/pi/poolServer/blink.js:8
line.requestOutputMode();
     ^

Error: EBUSY, Device or resource busy
    at Object.<anonymous> (/home/pi/poolServer/blink.js:8:6)
    at Module._compile (node:internal/modules/cjs/loader:1241:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1295:10)
    at Module.load (node:internal/modules/cjs/loader:1091:32)
    at Module._load (node:internal/modules/cjs/loader:938:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:83:12)
    at node:internal/main/run_main_module:23:47 {
  errno: 16,
  code: 'EBUSY',
  syscall: '::requestOutputMode'

Code:

const { version, Chip, Line } = require("node-libgpiod");

global.chip = new Chip(0);
const pin = 17;
global.line = new Line(chip, pin); // relay on GPIO17
let count = 10;

console.log(version());
line.requestOutputMode();

const blink = () => {
  if(count){
    line.setValue(count-- % 2);
    console.log("set pin", pin, "to", count % 2 );
    setTimeout(blink,1000);
  } // else line.release();
  // not needed, libgpiod releases resources on process exit
};

setTimeout(blink,1000);