# YF-S201 Water Flow Sensor - Help with Require

**URL:** <https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587>\
**Category:** General\
**Created:** [23 July 2020 07:34 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587 "2020-07-23T07:34:06Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [23 July 2020 07:34 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/1 "2020-07-23T07:34:07Z")

</div>

Hi. I'm trying to use YF-S201. I found a package for it. Here is the link to that:

> **[water-flow-sensor](https://www.npmjs.com/package/water-flow-sensor)**
>
> Get flow rate and volume consumption from water flow sensors

I never worked with a package before. I don't know what to do. I looked at a few similar things, but I didn't understand it that much. After changing the settings file, what should I do? Copy paste the entire code block in this link to a function, and that is it?

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [24 July 2020 08:26 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/2 "2020-07-24T08:26:58Z")

</div>

Anyone? I am reading about how to use packages like this one, but I don't understand it fully.

---

<div class="post-metadata">

**Author:** ![cymplecy](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cymplecy/32/2773_2.png) [@cymplecy](https://discourse.nodered.org/u/cymplecy)\
**Post date:** [24 July 2020 08:33 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/3 "2020-07-24T08:33:15Z")

</div>

Unfortunately, the package is 3 years old and the github page doesn't exist

It probably not worth effort as the chances of getting it working is small

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [24 July 2020 08:37 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/4 "2020-07-24T08:37:27Z")

</div>

Thanks for the reply.

Can you still guide me? Maybe it could work.

Also, I must use a water flow sensor. Are there any sensors that you would recommend?

---

<div class="post-metadata">

**Author:** ![cymplecy](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cymplecy/32/2773_2.png) [@cymplecy](https://discourse.nodered.org/u/cymplecy)\
**Post date:** [24 July 2020 08:40 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/5 "2020-07-24T08:40:07Z")

</div>

> [@cymplecy](#):
>
> It probably not worth effort as the chances of getting it working is small

and I don't have any experience of water flow sensors so can't help with that either

Sorry

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [24 July 2020 08:52 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/6 "2020-07-24T08:52:13Z")

</div>

Thanks anyway.

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [24 July 2020 08:57 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/7 "2020-07-24T08:57:45Z")

</div>

You can include a non node-red nodejs package in node-red.

I can show you how but you will need to figure out how to use the code.

Follow the below link (but where ever you see `tinycolor2.js` or `tinycolor2` change that to `water-flow-sensor`)...

[https://flows.nodered.org/flow/195773d3b493d81c9bf012f64da02ea3](https://flows.nodered.org/flow/195773d3b493d81c9bf012f64da02ea3)

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [27 July 2020 07:41 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/8 "2020-07-27T07:41:44Z")

</div>

I wrote (because it doesn't allow "-", also tried waterflowsensor):

```auto
      wfs: require('water-flow-sensor')

```

instead of:

```auto
      tinycolor: require('tinycolor2')

```

and I got these lines when I tried to restart:

```auto
> Error loading settings file: /home/pi/.node-red/settings.js
> Error: libnode.so.64: cannot open shared object file: No such file or directory
> at Object.Module._extensions..node (internal/modules/cjs/loader.js:1188:18)
> at Module.load (internal/modules/cjs/loader.js:986:32)
> at Function.Module._load (internal/modules/cjs/loader.js:879:14)
> at Module.require (internal/modules/cjs/loader.js:1026:19)
> at require (internal/modules/cjs/helpers.js:72:18)
> at bindings (/home/pi/.node-red/node_modules/epoll/node_modules/bindings/bindings.js:84:48)
> at Object.<anonymous> (/home/pi/.node-red/node_modules/epoll/epoll.js:1:37)
> at Module._compile (internal/modules/cjs/loader.js:1138:30)
> at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
> at Module.load (internal/modules/cjs/loader.js:986:32)

```

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [27 July 2020 07:57 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/9 "2020-07-27T07:57:03Z")

</div>

Because I'm not psychic, I have to ask...

Did you `npm install water-flow-sensor`?

Have you verified `home/pi/.node-red/node_modules/water-flow-sensor` exists and that it has something inside?

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [27 July 2020 07:58 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/10 "2020-07-27T07:58:34Z")

</div>

If you did install it then show us what you have in settings.js, including the lines around it.

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [27 July 2020 08:15 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/11 "2020-07-27T08:15:24Z")

</div>

I installed it earlier. Checked the file, and saw it. Ran npm line again, this is the result:

```auto
pi@raspberrypi:~/.node-red $ npm install water-flow-sensor
+ water-flow-sensor@1.0.1
updated 1 package and audited 180 packages in 12.256s

2 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

pi@raspberrypi:~/.node-red $ npm fund
node-red-project@0.0.1
├─┬ https://ko-fi.com/tunnckoCore/commissions
│ └── formidable@1.2.2
└─┬ https://github.com/sponsors/sindresorhus
  └── mimic-response@2.1.0

```

I don't know which part to send, so here is the entire settings.js:

```auto
/**
 * Copyright JS Foundation and other contributors, http://js.foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/

module.exports = {
    // the tcp port that the Node-RED web server is listening on
    uiPort: process.env.PORT || 1880,

    // By default, the Node-RED UI accepts connections on all IPv4 interfaces.
    // To listen on all IPv6 addresses, set uiHost to "::",
    // The following property can be used to listen on a specific interface. For
    // example, the following would only allow connections from the local machine.
    //uiHost: "127.0.0.1",

    // Retry time in milliseconds for MQTT connections
    mqttReconnectTime: 15000,

    // Retry time in milliseconds for Serial port connections
    serialReconnectTime: 15000,

    // Retry time in milliseconds for TCP socket connections
    //socketReconnectTime: 10000,

    // Timeout in milliseconds for TCP server socket connections
    // defaults to no timeout
    //socketTimeout: 120000,

    // Maximum number of messages to wait in queue while attempting to connect to TCP socket
    // defaults to 1000
    //tcpMsgQueueSize: 2000,

    // Timeout in milliseconds for HTTP request connections
    // defaults to 120 seconds
    //httpRequestTimeout: 120000,

    // The maximum length, in characters, of any message sent to the debug sidebar tab
    debugMaxLength: 1000,

    // The maximum number of messages nodes will buffer internally as part of their
    // operation. This applies across a range of nodes that operate on message sequences.
    // defaults to no limit. A value of 0 also means no limit is applied.
    //nodeMessageBufferMaxLength: 0,

    // To disable the option for using local files for storing keys and certificates in the TLS configuration
    // node, set this to true
    //tlsConfigDisableLocalFiles: true,

    // Colourise the console output of the debug node
    //debugUseColors: true,

    // The file containing the flows. If not set, it defaults to flows_<hostname>.json
    //flowFile: 'flows.json',

    // To enabled pretty-printing of the flow within the flow file, set the following
    // property to true:
    //flowFilePretty: true,

    // By default, credentials are encrypted in storage using a generated key. To
    // specify your own secret, set the following property.
    // If you want to disable encryption of credentials, set this property to false.
    // Note: once you set this property, do not change it - doing so will prevent
    // node-red from being able to decrypt your existing credentials and they will be
    // lost.
    //credentialSecret: "a-secret-key",

    // By default, all user data is stored in a directory called `.node-red` under
    // the user's home directory. To use a different location, the following
    // property can be used
    //userDir: '/home/nol/.node-red/',

    // Node-RED scans the `nodes` directory in the userDir to find local node files.
    // The following property can be used to specify an additional directory to scan.
    //nodesDir: '/home/nol/.node-red/nodes',

    // By default, the Node-RED UI is available at http://localhost:1880/
    // The following property can be used to specify a different root path.
    // If set to false, this is disabled.
    //httpAdminRoot: '/admin',

    // Some nodes, such as HTTP In, can be used to listen for incoming http requests.
    // By default, these are served relative to '/'. The following property
    // can be used to specifiy a different root path. If set to false, this is
    // disabled.
    //httpNodeRoot: '/red-nodes',

    // The following property can be used in place of 'httpAdminRoot' and 'httpNodeRoot',
    // to apply the same root to both parts.
    //httpRoot: '/red',

    // When httpAdminRoot is used to move the UI to a different root path, the
    // following property can be used to identify a directory of static content
    // that should be served at http://localhost:1880/.
    httpStatic: '/home/pi/.node-red/',

    // The maximum size of HTTP request that will be accepted by the runtime api.
    // Default: 5mb
    //apiMaxLength: '5mb',

    // If you installed the optional node-red-dashboard you can set it's path
    // relative to httpRoot
    //ui: { path: "ui" },

    // Securing Node-RED
    // -----------------
    // To password protect the Node-RED editor and admin API, the following
    // property can be used. See http://nodered.org/docs/security.html for details.
    //adminAuth: {
    // type: "credentials",
    // users: [{
    // username: "admin",
    // password: "$2a$08$zZWtXTja0fB1pzD4sHCMyOCMYz2Z6dNbM6tl8sJogENOMcxWV9DN.",
    // permissions: "*"
    // }]
    //},

    // To password protect the node-defined HTTP endpoints (httpNodeRoot), or
    // the static content (httpStatic), the following properties can be used.
    // The pass field is a bcrypt hash of the password.
    // See http://nodered.org/docs/security.html#generating-the-password-hash
    //httpNodeAuth: {user:"user",pass:"$2a$08$zZWtXTja0fB1pzD4sHCMyOCMYz2Z6dNbM6tl8sJogENOMcxWV9DN."},
    //httpStaticAuth: {user:"user",pass:"$2a$08$zZWtXTja0fB1pzD4sHCMyOCMYz2Z6dNbM6tl8sJogENOMcxWV9DN."},

    // The following property can be used to enable HTTPS
    // See http://nodejs.org/api/https.html#https_https_createserver_options_requestlistener
    // for details on its contents.
    // This property can be either an object, containing both a (private) key and a (public) certificate,
    // or a function that returns such an object:
    //// https object:
    //https: {
    // key: require("fs").readFileSync('privkey.pem'),
    // cert: require("fs").readFileSync('cert.pem')
    //},
    ////https function:
    // https: function() {
    // // This function should return the options object, or a Promise
    // // that resolves to the options object
    // return {
    // key: require("fs").readFileSync('privkey.pem'),
    // cert: require("fs").readFileSync('cert.pem')
    // }
    // },

    // The following property can be used to refresh the https settings at a
    // regular time interval in hours.
    // This requires:
    // - the `https` setting to be a function that can be called to get
    // the refreshed settings.
    // - Node.js 11 or later.
    //httpsRefreshInterval : 12,

    // The following property can be used to cause insecure HTTP connections to
    // be redirected to HTTPS.
    //requireHttps: true,

    // The following property can be used to disable the editor. The admin API
    // is not affected by this option. To disable both the editor and the admin
    // API, use either the httpRoot or httpAdminRoot properties
    //disableEditor: false,

    // The following property can be used to configure cross-origin resource sharing
    // in the HTTP nodes.
    // See https://github.com/troygoode/node-cors#configuration-options for
    // details on its contents. The following is a basic permissive set of options:
    //httpNodeCors: {
    // origin: "*",
    // methods: "GET,PUT,POST,DELETE"
    //},

    // If you need to set an http proxy please set an environment variable
    // called http_proxy (or HTTP_PROXY) outside of Node-RED in the operating system.
    // For example - http_proxy=http://myproxy.com:8080
    // (Setting it here will have no effect)
    // You may also specify no_proxy (or NO_PROXY) to supply a comma separated
    // list of domains to not proxy, eg - no_proxy=.acme.co,.acme.co.uk

    // The following property can be used to add a custom middleware function
    // in front of all http in nodes. This allows custom authentication to be
    // applied to all http in nodes, or any other sort of common request processing.
    //httpNodeMiddleware: function(req,res,next) {
    // // Handle/reject the request, or pass it on to the http in node by calling next();
    // // Optionally skip our rawBodyParser by setting this to true;
    // //req.skipRawBodyParser = true;
    // next();
    //},

    // The following property can be used to add a custom middleware function
    // in front of all admin http routes. For example, to set custom http
    // headers
    // httpAdminMiddleware: function(req,res,next) {
    // // Set the X-Frame-Options header to limit where the editor
    // // can be embedded
    // //res.set('X-Frame-Options', 'sameorigin');
    // next();
    // },

    // The following property can be used to pass custom options to the Express.js
    // server used by Node-RED. For a full list of available options, refer
    // to http://expressjs.com/en/api.html#app.settings.table
    //httpServerOptions: { },

    // The following property can be used to verify websocket connection attempts.
    // This allows, for example, the HTTP request headers to be checked to ensure
    // they include valid authentication information.
    //webSocketNodeVerifyClient: function(info) {
    // // 'info' has three properties:
    // // - origin : the value in the Origin header
    // // - req : the HTTP request
    // // - secure : true if req.connection.authorized or req.connection.encrypted is set
    // //
    // // The function should return true if the connection should be accepted, false otherwise.
    // //
    // // Alternatively, if this function is defined to accept a second argument, callback,
    // // it can be used to verify the client asynchronously.
    // // The callback takes three arguments:
    // // - result : boolean, whether to accept the connection or not
    // // - code : if result is false, the HTTP error status to return
    // // - reason: if result is false, the HTTP reason string to return
    //},

    // The following property can be used to seed Global Context with predefined
    // values. This allows extra node modules to be made available with the
    // Function node.
    // For example,
    // functionGlobalContext: { os:require('os') }
    // can be accessed in a function block as:
    // global.get("os")
    functionGlobalContext: {
        // os:require('os'),
        // jfive:require("johnny-five"),
        // j5board:require("johnny-five").Board({repl:false})
    },
    // `global.keys()` returns a list of all properties set in global context.
    // This allows them to be displayed in the Context Sidebar within the editor.
    // In some circumstances it is not desirable to expose them to the editor. The
    // following property can be used to hide any property set in `functionGlobalContext`
    // from being list by `global.keys()`.
    // By default, the property is set to false to avoid accidental exposure of
    // their values. Setting this to true will cause the keys to be listed.
    exportGlobalContextKeys: false,

    // Context Storage
    // The following property can be used to enable context storage. The configuration
    // provided here will enable file-based context that flushes to disk every 30 seconds.
    // Refer to the documentation for further options: https://nodered.org/docs/api/context/
    //
    //contextStorage: {
    // default: {
    // module:"localfilesystem"
    // },
    //},

    // The following property can be used to order the categories in the editor
    // palette. If a node's category is not in the list, the category will get
    // added to the end of the palette.
    // If not set, the following default order is used:
    //paletteCategories: ['subflows', 'common', 'function', 'network', 'sequence', 'parser', 'storage'],

    // Configure the logging output
    logging: {
        // Only console logging is currently supported
        console: {
            // Level of logging to be recorded. Options are:
            // fatal - only those errors which make the application unusable should be recorded
            // error - record errors which are deemed fatal for a particular request + fatal errors
            // warn - record problems which are non fatal + errors + fatal errors
            // info - record information about the general running of the application + warn + error + fatal errors
            // debug - record information which is more verbose than info + info + warn + error + fatal errors
            // trace - record very detailed logging + debug + info + warn + error + fatal errors
            // off - turn off all logging (doesn't affect metrics or audit)
            level: "info",
            // Whether or not to include metric events in the log output
            metrics: false,
            // Whether or not to include audit events in the log output
            audit: false
        }
    },

    // Customising the editor
    editorTheme: {
        projects: {
            // To enable the Projects feature, set this value to true
            enabled: false
        }
    }
}

```

Edit: I was writing that require line here:

```auto
functionGlobalContext: {
------>Here
        // os:require('os'),
        // jfive:require("johnny-five"),
        // j5board:require("johnny-five").Board({repl:false})
    },

```

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [27 July 2020 08:22 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/12 "2020-07-27T08:22:14Z")

</div>

> [@oncdastan](#):
>
> ```auto
> functionGlobalContext: {
> // os:require('os'),
> // jfive:require("johnny-five"),
> // j5board:require("johnny-five").Board({repl:false})
> },
> 
> ```

should be

```
functionGlobalContext: {
  wfs: require('water-flow-sensor')
},

```

Can you verify the directory `water-flow-sensor` exists inside `home/pi/.node-red/node_modules`?

Then in a function node you should be able to get a reference to `wfs = global.get("wfs")`

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [27 July 2020 08:52 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/13 "2020-07-27T08:52:10Z")

</div>

![2020-07-27-115122_1920x1080_scrot](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/2/b/2bde673d4e72cdff44cda69b4c5cf469e9a708d4.png)

Edit: I tried with and without deleting those 3 lines that were already there before, and pasting the line you wrote. Same results in both ways. I know it is commented out, so those won't work, but I tried it anyway.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [27 July 2020 09:13 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/14 "2020-07-27T09:13:18Z")

</div>

What happens if you rename settings.js and restart node-red. It should create a new default settings file so that at least node-red should start up.

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [27 July 2020 09:16 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/15 "2020-07-27T09:16:56Z")

</div>

Yeah, it did create a new one.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [27 July 2020 09:19 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/16 "2020-07-27T09:19:30Z")

</div>

Does node red now start ok? If so then add the new bit again.

---

<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [27 July 2020 09:22 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/17 "2020-07-27T09:22:51Z")

</div>

It started okay. I got the same error when I wrote that line, saved it, and tried to restart Node Red.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [27 July 2020 09:30 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/18 "2020-07-27T09:30:14Z")

</div>

Strange, it is ok for me. Can you copy/paste here what you have for functionGlobalContext and a few lines either side.

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [27 July 2020 09:31 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/19 "2020-07-27T09:31:10Z")

</div>

looking at that error stack, it looks like it has a problem with `epoll`.

`epoll` is required by `onoff`

the `water-flow-sensor` NPM page states "onoff ^1.1.2" is required

as the source code for `water-flow-sensor` isnt in github, I cant see if it actually DOES include `onoff` in its package.

so - you could try manually adding `onoff` and `epoll` (if they dont already exist in your node\_modules directory)

EDIT...  
as `onoff` is now at V6.0.0 in NPM you might need to specifically install onoff@1.1.2

The truth is, this package is dead - no source, no updates for 3y. You would be better off looking for alternative means. I bet under the hood, it doesnt really do much.

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<div class="post-metadata">

**Author:** ![oncdastan](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Post date:** [27 July 2020 09:31 UTC](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587/20 "2020-07-27T09:31:35Z")

</div>

Sure. Here they are:

```auto
// The following property can be used to seed Global Context with predefined
    // values. This allows extra node modules to be made available with the
    // Function node.
    // For example,
    // functionGlobalContext: { os:require('os') }
    // can be accessed in a function block as:
    // global.get("os")
    functionGlobalContext: {
	wfs: require('water-flow-sensor')
        // os:require('os'),
        // jfive:require("johnny-five"),
        // j5board:require("johnny-five").Board({repl:false})
    },
    // `global.keys()` returns a list of all properties set in global context.
    // This allows them to be displayed in the Context Sidebar within the editor.
    // In some circumstances it is not desirable to expose them to the editor. The
    // following property can be used to hide any property set in `functionGlobalContext`
    // from being list by `global.keys()`.
    // By default, the property is set to false to avoid accidental exposure of
    // their values. Setting this to true will cause the keys to be listed.
    exportGlobalContextKeys: false,

```

[Next page](https://discourse.nodered.org/t/yf-s201-water-flow-sensor-help-with-require/30587.md?page=2)