Cannot get pwm demo running

[LockonS]

Node.js version: 10.8.0 pigpio version: 1.1.2 Device: Raspberry Pi 3B+ pigpio C library already installed and started as root. While trying to get demo running, it always output errors as below.

2018-08-05 21:17:28 initInitialise: Can't lock /var/run/pigpio.pid
/root/pi-gpio-trial/node_modules/pigpio/pigpio.js:16
    pigpio.gpioInitialise();
           ^

Error: pigpio error -1 in gpioInitialise
    at initializePigpio (/root/pi-gpio-trial/node_modules/pigpio/pigpio.js:16:12)
    at new Gpio (/root/pi-gpio-trial/node_modules/pigpio/pigpio.js:29:5)
    at Object.<anonymous> (/root/pi-gpio-trial/test.js:3:13)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:742:12)
    at startup (internal/bootstrap/node.js:266:19)

And the demo that I tried to run is

const Gpio = require('pigpio').Gpio;

const led = new Gpio(17, {mode: Gpio.OUTPUT});

let dutyCycle = 0;

setInterval(() => {
  led.pwmWrite(dutyCycle);

  dutyCycle += 5;
  if (dutyCycle > 255) {
    dutyCycle = 0;
  }
}, 20);

I tried to run the script as pi with sudo or directly run the script as root, but still cannot get it to run properly.

[onokje]

That happens if the gpio is already in use by another process. Maybe you have it running twice? Quit other processes that may use the gpio and try again.

[LockonS]

@onokje Thanks for the reply, but I am pretty sure that this node.js application is the only processess that use the gpio.

[fivdi]

@LockonS please verify that the pigpiod daemon is not running. If the pigpiod daemon is running the pigpio Node.js module can not be run.

[LockonS]

@fivdi Thanks a lot and it works perfectly now. I was so stupid to miss the statement in readme. Maybe highlight this part in readme could save the some others in case I was not the only one to overlock that.

[fivdi]

@LockonS Yes, highlighting the appropriate section of the readme would help here. Thank you for the suggestion.

fixed with db033b544d0bc8672546c765ced3cdd744bb8adb