# Jsmodbus as external javascript in a function node

**URL:** <https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391>\
**Category:** General\
**Created:** [28 January 2022 09:31 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391 "2022-01-28T09:31:24Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 09:31 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/1 "2022-01-28T09:31:24Z")

</div>

I know that is node-red-contrib-modbus, but I want to use clear jsmodbus inside node-red.  
Inside .node-red folder I install jsmodbus ('npm install -g jsmodbus')  
my settings.js

```auto
    functionGlobalContext: {
		jsmodbus: require('jsmodbus'),
		net: require('net')
    },

```

my function

```auto
    // create a tcp modbus client
    
let Modbus = global.get('jsmodbus');
let net = global.get('net');
let socket = new net.Socket();
let client = new Modbus.client.TCP(socket);
let options = {
  host: "10.0.0.66",
  port: 502
};

socket.on("connect", function() {
  client
    .readHoldingRegisters(5,1)
    .then(function(resp) {
      msg.m_response = resp.response._body;
      socket.end();
    })
    .catch(function() {
      console.error(
        require("util").inspect(arguments, {
          depth: null
        })
      );
      socket.end();
    });
});

socket.connect(options);

return msg;

```

```auto
[{"id":"6dc680ce450d84b1","type":"tab","label":"jsmodbus","disabled":false,"info":"","env":[]},{"id":"62559f47f6818b55","type":"function","z":"6dc680ce450d84b1","name":"","func":" // create a tcp modbus client\n \nlet Modbus = global.get('jsmodbus');\nlet net = global.get('net');\nlet socket = new net.Socket();\nlet client = new Modbus.client.TCP(socket);\nlet options = {\n host: \"10.0.0.66\",\n port: 502\n};\n\nsocket.on(\"connect\", function() {\n client\n .readHoldingRegisters(5,1)\n .then(function(resp) {\n msg.m_response = resp.response._body;\n socket.end();\n })\n .catch(function() {\n console.error(\n require(\"util\").inspect(arguments, {\n depth: null\n })\n );\n socket.end();\n });\n});\n\n\nsocket.connect(options);\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":240,"y":120,"wires":[["abce1ad369e230cc"]]},{"id":"fed32ff3f60dbcfe","type":"inject","z":"6dc680ce450d84b1","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":90,"y":120,"wires":[["62559f47f6818b55"]]},{"id":"abce1ad369e230cc","type":"debug","z":"6dc680ce450d84b1","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":420,"y":120,"wires":[]}]

```

and my error  
 ![obraz](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/d/5d439ff7c627dafc48c7ff9fa479b26e8d42dd89.png)

Any idea?

---

<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:** [28 January 2022 09:43 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/2 "2022-01-28T09:43:08Z")

</div>

The obvious questions first

- can this instance of node-red ping `10.0.0.66` ?
- is the device online and is port 502 the correct port?

An end to end test could be performed by using node-red-node-ping (so that the node-red instance from within node env does the pinging)

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 09:46 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/3 "2022-01-28T09:46:20Z")

</div>

Yes. I tested by Modbus Pool and its ok.  
This error crashed node-red and I must have start node-red again.

---

<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:** [28 January 2022 09:48 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/4 "2022-01-28T09:48:11Z")

</div>

> [@ketpa](#):
>
> Yes. I tested by Modbus Pool and its ok.

That does not verify the node-red instance can contact `10.0.0.66`  
Please do a ping check from within node-red to the end device.

Also, is node-red running in docker?

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 10:21 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/5 "2022-01-28T10:21:36Z")

</div>

Node-red is not from docker.  
Ping from node-red is ok.  
function from node-red-contrib-modbus give me values.  
Problem is with net library I think.

---

<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:** [28 January 2022 10:34 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/6 "2022-01-28T10:34:41Z")

</div>

I doubt the `net` library is a problem (thats node native lib)

if anything the issue is with `jsmodbus` or your usage.

What is wrong with using `node-red-contrib-modbus` anyway?

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 10:41 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/7 "2022-01-28T10:41:59Z")

</div>

I give from database register address and Ip.  
I used ModbusFlexConnector from `node-red-contrib-modbus` and it's work, but it very slow for many values.

---

<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:** [28 January 2022 10:42 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/8 "2022-01-28T10:42:50Z")

</div>

> [@ketpa](#):
>
> but it very slow for many values

Are you reading values individually or are you reading more than one at a time?

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 10:45 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/9 "2022-01-28T10:45:17Z")

</div>

Indyvidually and packages. I have about 20 IP devices and about 100 register for each.

---

<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:** [28 January 2022 11:10 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/10 "2022-01-28T11:10:34Z")

</div>

> [@ketpa](#):
>
> and about 100 register for each.

Are the registers spread out or near each other?

The point I am getting to is...

- If (for example) you request MB registers 11, 13, 15, 44, 66, 68, 69, 70, 80, 88, 101 ~ 130, 150~189 as 12 reads - that is **much more expensive** than requesting 2 reads of `10~99` and `100~189`

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 13:15 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/11 "2022-01-28T13:15:18Z")

</div>

Yes, but sometimes is situation that 11,13 but register 12 doesn't exist.  
I must have refresh time 1-5 second for all points. If I have many  
 ![obraz](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/6/4/646ebe8fd9f20c98e14aa946cf409811af462cfd.png) block it's ok, but with that  
 ![obraz](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/1/6/16c82339bb0a65e56ca8a3a58c84a58df31d0f71.png) I must use delay.  
I have something like this

 ![obraz](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/2/d23a1e651c2268085ab2e024bf0d50b0c1c53105.png)  
It's not all.  
I have table when I set value to devices by modbus. Before I used php, but now, I try to move to node-red 🙂

---

<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:** [28 January 2022 13:21 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/12 "2022-01-28T13:21:05Z")

</div>

> [@ketpa](#):
>
> Yes, but sometimes is situation that 11,13 but register 12 doesn't exist

Do you mean that if the device does not have a register 12 that the communication fails?

To be more precise...  
If you requested 3 registers starting from register 11 even though you don't _need_ register 12, does the modbus communication work or does it fail?

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 13:23 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/13 "2022-01-28T13:23:56Z")

</div>

> [@Steve-Mcl](#):
>
> If you requested 3 registers starting from register 11 even though you don't _need_ register 12, does the modbus communication work or does it fail?

Fail, or I waiting as timeout finish. I can't use it.  
Is not situation that I don't need 12 register. It give me '0' or something.  
I tested that situation.

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 13:28 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/14 "2022-01-28T13:28:02Z")

</div>

In pure js I write this and it works in node.js

```auto
const Modbus = require('jsmodbus')
const net = require('net')
const socket = new net.Socket()
const client = new Modbus.client.TCP(socket, 1)
const options = {
'host' : '10.0.0.66',
'port' : 502
}

//const client = new modbus.client.TCP(socket)

socket.on('connect', function () {
  client.readHoldingRegisters(8737, 4)
    .then(function (resp) {
      console.log(resp.response._body.valuesAsArray)
      socket.end()
    }).catch(function () {
      console.error(require('util').inspect(arguments, {
        depth: null
      }))
      socket.end()
    })
})

socket.on('error', console.error)
socket.connect(options)

```

---

<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:** [28 January 2022 13:34 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/15 "2022-01-28T13:34:05Z")

</div>

> [@ketpa](#):
>
> Fail, or I waiting as timeout finish. I can't use it.  
> Is not situation that I don't need 12 register. It give me '0' or something

Ok understand.

Can you share your flow and some sample data (capture the payload from your database debug node & paste it into an inject node) so I can simulate your issue.

I think I know your issue with the contrib node.

If that doesn't work, I'll help you get the function node working.

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 13:56 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/16 "2022-01-28T13:56:22Z")

</div>

Sample with ModbusFlexConnector

```auto
[{"id":"ca6d31db8909b2f6","type":"inject","z":"13b11b04.342725","name":"","repeat":"3600","crontab":"","once":false,"onceDelay":0.1,"topic":"","payloadType":"date","x":130,"y":1220,"wires":[["ec442f7307e32a81","acac9bff0a533975"]]},{"id":"ec442f7307e32a81","type":"function","z":"13b11b04.342725","name":"","func":"var table1 = msg.c1;\nvar query = \"SELECT delta, nazwa, host, modbus_id from temp_tid where delta>0\";\nmsg.topic = query;\nreturn msg;","outputs":1,"noerr":0,"x":300,"y":1220,"wires":[["36ac1d98a418f21c"]]},{"id":"36ac1d98a418f21c","type":"mysql","z":"13b11b04.342725","mydb":"36c886e2.421612","name":"db","x":430,"y":1220,"wires":[["ebe864bd81c84cc5"]]},{"id":"ebe864bd81c84cc5","type":"debug","z":"13b11b04.342725","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":600,"y":1220,"wires":[]},{"id":"931f37b035f53f14","type":"modbus-flex-connector","z":"13b11b04.342725","name":"","maxReconnectsPerMinute":4,"emptyQueue":false,"showStatusActivities":true,"showErrors":false,"server":"5cac7a09.32364c","x":630,"y":1320,"wires":[["bb18a1e21ba1d629"]]},{"id":"c4ae37ebd438db19","type":"modbus-flex-sequencer","z":"13b11b04.342725","name":"sequencer 1","sequences":[{"name":"1","unitid":"1","fc":"FC4","address":"10009","quantity":"1"}],"server":"5cac7a09.32364c","showStatusActivities":true,"showErrors":true,"logIOActivities":false,"useIOFile":false,"ioFile":"","useIOForPayload":false,"emptyMsgOnFail":false,"keepMsgProperties":false,"x":1010,"y":1320,"wires":[["bc2bc1764d1916c2","e12b723b657d0bcb"],[]]},{"id":"bc2bc1764d1916c2","type":"debug","z":"13b11b04.342725","name":"output","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":1170,"y":1320,"wires":[]},{"id":"bb18a1e21ba1d629","type":"delay","z":"13b11b04.342725","name":"","pauseType":"delay","timeout":"9","timeoutUnits":"seconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"outputs":1,"x":840,"y":1320,"wires":[["c4ae37ebd438db19"]]},{"id":"52b1389934190985","type":"function","z":"13b11b04.342725","name":"f1","func":"var devices1 =[{\"delta\":1,\"nazwa\":\"ED_9373\",\"host\":\"10.0.0.202\",\"modbus_id\":8},{\"delta\":2,\"nazwa\":\"ED_9376\",\"host\":\"10.0.0.132\",\"modbus_id\":2},{\"delta\":3,\"nazwa\":\"ED_9377\",\"host\":\"10.0.0.201\",\"modbus_id\":4},{\"delta\":4,\"nazwa\":\"ED_9375\",\"host\":\"10.0.0.203\",\"modbus_id\":9},{\"delta\":5,\"nazwa\":\"ED_9379\",\"host\":\"10.0.0.204\",\"modbus_id\":5},{\"delta\":6,\"nazwa\":\"ED_9374\",\"host\":\"10.0.0.203\",\"modbus_id\":3},{\"delta\":8,\"nazwa\":\"ED_9380\",\"host\":\"10.0.0.202\",\"modbus_id\":7},{\"delta\":9,\"nazwa\":\"ED_9381\",\"host\":\"10.0.0.203\",\"modbus_id\":6},{\"delta\":7,\"nazwa\":\"ED_9378\",\"host\":\"10.0.0.131\",\"modbus_id\":10}];\nvar devices = msg.payload;\n\n\ndevices.forEach(dev => {\n\n node.send({\n \"topic\": dev.nazwa,\n \"payload\": {\n \"connectorType\" : \"TCP\",\n \"tcpHost\": dev.host,\n \"tcpPort\": \"502\",\n \"unitId\": dev.modbus_id\n },\n \"sequences\": [\n {\n name: dev.host,\n unitid: dev.modbus_id,\n fc: 4,\n address: 10009,\n quantity: 1\n }\n]\n });\n\n})\n\n\n\nreturn null;","outputs":1,"noerr":0,"x":230,"y":1320,"wires":[["589fdf93fe8d790d","297df7472b57f343"]]},{"id":"589fdf93fe8d790d","type":"debug","z":"13b11b04.342725","name":"","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":410,"y":1360,"wires":[]},{"id":"297df7472b57f343","type":"delay","z":"13b11b04.342725","name":"","pauseType":"rate","timeout":"5","timeoutUnits":"seconds","rate":"1","nbRateUnits":"10","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"outputs":1,"x":400,"y":1320,"wires":[["931f37b035f53f14"]]},{"id":"e12b723b657d0bcb","type":"function","z":"13b11b04.342725","name":"","func":"var table = 'alarmy';\nvar bat = msg.payload[0];\nvar modbus_id = msg.unitId;\nvar query = '';\n\n\nquery= `UPDATE temp_tid set bat = ${bat} WHERE modbus_id= ${modbus_id};`;\n\n\nmsg.query = query;\nmsg.topic = query;\n\n\nreturn msg;\n\n\n\n\n","outputs":1,"noerr":0,"x":1020,"y":1400,"wires":[["9cba012d79a7d3e1"]]},{"id":"9cba012d79a7d3e1","type":"mysql","z":"13b11b04.342725","mydb":"36c886e2.421612","name":"db","x":1150,"y":1400,"wires":[[]]},{"id":"59dd46656ff38922","type":"comment","z":"13b11b04.342725","name":"json","info":"[{\"delta\":1,\"nazwa\":\"ED_9373\",\"host\":\"192.168.98.201\",\"modbus_id\":8},{\"delta\":2,\"nazwa\":\"ED_9376\",\"host\":\"192.168.98.203\",\"modbus_id\":2},{\"delta\":3,\"nazwa\":\"ED_9377\",\"host\":\"192.168.98.202\",\"modbus_id\":4},{\"delta\":4,\"nazwa\":\"ED_9375\",\"host\":\"192.168.98.203\",\"modbus_id\":9},{\"delta\":5,\"nazwa\":\"ED_9379\",\"host\":\"192.168.98.204\",\"modbus_id\":5},{\"delta\":6,\"nazwa\":\"ED_9374\",\"host\":\"192.168.98.203\",\"modbus_id\":4},{\"delta\":8,\"nazwa\":\"ED_9380\",\"host\":\"192.168.98.202\",\"modbus_id\":7},{\"delta\":9,\"nazwa\":\"ED_9381\",\"host\":\"192.168.1.132\",\"modbus_id\":6},{\"delta\":7,\"nazwa\":\"ED_9378\",\"host\":\"10.0.0.1\",\"modbus_id\":10}]","x":770,"y":1220,"wires":[]},{"id":"acac9bff0a533975","type":"function","z":"13b11b04.342725","name":"","func":"msg.payload = [{\"delta\":1,\"nazwa\":\"ED_9373\",\"host\":\"192.168.98.201\",\"modbus_id\":8},{\"delta\":2,\"nazwa\":\"ED_9376\",\"host\":\"192.168.98.203\",\"modbus_id\":2},{\"delta\":3,\"nazwa\":\"ED_9377\",\"host\":\"192.168.98.202\",\"modbus_id\":4},{\"delta\":4,\"nazwa\":\"ED_9375\",\"host\":\"192.168.98.203\",\"modbus_id\":9},{\"delta\":5,\"nazwa\":\"ED_9379\",\"host\":\"192.168.98.204\",\"modbus_id\":5},{\"delta\":6,\"nazwa\":\"ED_9374\",\"host\":\"192.168.98.203\",\"modbus_id\":4},{\"delta\":8,\"nazwa\":\"ED_9380\",\"host\":\"192.168.98.202\",\"modbus_id\":7},{\"delta\":9,\"nazwa\":\"ED_9381\",\"host\":\"192.168.1.132\",\"modbus_id\":6},{\"delta\":7,\"nazwa\":\"ED_9378\",\"host\":\"10.0.0.1\",\"modbus_id\":10}];\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":100,"y":1320,"wires":[["52b1389934190985"]]},{"id":"36c886e2.421612","type":"MySQLdatabase","name":"","host":"localhost","port":"3306","db":"chema","tz":"","charset":"UTF8"},{"id":"5cac7a09.32364c","type":"modbus-client","name":"","clienttype":"tcp","bufferCommands":true,"stateLogEnabled":false,"queueLogEnabled":false,"tcpHost":"192.168.98.203","tcpPort":"502","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB","serialType":"RTU-BUFFERD","serialBaudrate":"9600","serialDatabits":"8","serialStopbits":"1","serialParity":"none","serialConnectionDelay":"100","unit_id":"0","commandDelay":"1","clientTimeout":"1000","reconnectOnTimeout":false,"reconnectTimeout":"2000","parallelUnitIdsAllowed":true}]

```

---

<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [28 January 2022 14:01 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/17 "2022-01-28T14:01:12Z")

</div>

Sample with Modbus Read

```auto
[{"id":"7eef272d35972c7e","type":"modbus-read","z":"6dc680ce450d84b1","name":"","topic":"","showStatusActivities":true,"logIOActivities":false,"showErrors":true,"unitid":"","dataType":"HoldingRegister","adr":"8637","quantity":"100","rate":"1","rateUnit":"h","delayOnStart":false,"startDelayTime":"","server":"81dd93cb.5ed208","useIOFile":false,"ioFile":"","useIOForPayload":false,"emptyMsgOnFail":true,"x":450,"y":360,"wires":[["5b58d539eec7b040"],[]]},{"id":"5b58d539eec7b040","type":"debug","z":"6dc680ce450d84b1","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":640,"y":360,"wires":[]},{"id":"81dd93cb.5ed208","type":"modbus-client","name":"10.0.0.151","clienttype":"tcp","bufferCommands":true,"stateLogEnabled":false,"queueLogEnabled":false,"tcpHost":"10.0.0.151","tcpPort":"502","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB","serialType":"RTU-BUFFERD","serialBaudrate":"9600","serialDatabits":"8","serialStopbits":"1","serialParity":"none","serialConnectionDelay":"100","serialAsciiResponseStartDelimiter":"","unit_id":"1","commandDelay":"1","clientTimeout":"10000","reconnectOnTimeout":true,"reconnectTimeout":"20000","parallelUnitIdsAllowed":true}]

```

If some register not exist's I have error  
 ![obraz](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/a/3acf4f847ea3a4e2960af557f62361919aff8c9f.png)

---

<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:** [28 January 2022 14:20 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/18 "2022-01-28T14:20:20Z")

</div>

On that example, you are asking for 100 REG from 8637 (8637 ~ 8736) - is it not a case of going above some internal memory max location?

Or is it definitely some random unavailable address(es) inside that range?

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<div class="post-metadata">

**Author:** ![ketpa](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ketpa/32/42496_2.png) [@ketpa](https://discourse.nodered.org/u/ketpa)\
**Post date:** [29 January 2022 20:05 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/19 "2022-01-29T20:05:54Z")

</div>

> On that example, you are asking for 100 REG from 8637 (8637 ~ 8736) - is it not a case of going above some internal memory max location?

No, I tested 4 000 register (0-99, 100-199...4000) and it was OK. Refresh time 5 sec from PLC.

> Or is it definitely some random unavailable address(es) inside that range?

Yes. Some devices has separately range like 0-10 20-30 and address 11 will give unavailable error.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [30 March 2022 20:06 UTC](https://discourse.nodered.org/t/jsmodbus-as-external-javascript-in-a-function-node/57391/20 "2022-03-30T20:06:05Z")

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