# My modbus receives data but doesn't send data

**URL:** <https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760>\
**Category:** General\
**Tags:** modbus\
**Created:** [4 February 2022 09:49 UTC](https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760 "2022-02-04T09:49:50Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![fernando](https://avatars.discourse-cdn.com/v4/letter/f/779978/32.png) [@fernando](https://discourse.nodered.org/u/fernando)\
**Post date:** [4 February 2022 09:49 UTC](https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760/1 "2022-02-04T09:49:50Z")

</div>

Hi, I'm tying to get data from modbus tcp but I get error:

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/1/e/1ed3af286d70648be46660df0f0af9935eb7ff82.png)

I'm using **Waveshare rs485 to eth(b)** connected to **Eastron sdm630 modbus v2**.  
I have read the manuals and the connection of the cables is ok.

This is my Waveshare configuration:

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/4/5/454dc3bf94f814f47cf72d0786dcaa23bdf37843.png)

This is my simple flow just to receive data:

```auto
[
    {
        "id": "a3de20922655e292",
        "type": "tab",
        "label": "Flow 1",
        "disabled": false,
        "info": "",
        "env": []
    },
    {
        "id": "f59e084ca18cde41",
        "type": "inject",
        "z": "a3de20922655e292",
        "name": "",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "payload": "",
        "payloadType": "date",
        "x": 200,
        "y": 100,
        "wires": [
            [
                "8f9226772e8e20e7"
            ]
        ]
    },
    {
        "id": "30b93a5cf40f42a9",
        "type": "debug",
        "z": "a3de20922655e292",
        "name": "",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 610,
        "y": 140,
        "wires": []
    },
    {
        "id": "8f9226772e8e20e7",
        "type": "modbus-getter",
        "z": "a3de20922655e292",
        "name": "",
        "showStatusActivities": false,
        "showErrors": true,
        "logIOActivities": false,
        "unitid": "",
        "dataType": "InputRegister",
        "adr": "0",
        "quantity": "72",
        "server": "ccc8899221dfcc7e",
        "useIOFile": false,
        "ioFile": "",
        "useIOForPayload": false,
        "emptyMsgOnFail": false,
        "keepMsgProperties": false,
        "x": 400,
        "y": 120,
        "wires": [
            [],
            [
                "30b93a5cf40f42a9"
            ]
        ]
    },
    {
        "id": "ccc8899221dfcc7e",
        "type": "modbus-client",
        "name": "RS485",
        "clienttype": "tcp",
        "bufferCommands": true,
        "stateLogEnabled": false,
        "queueLogEnabled": false,
        "tcpHost": "10.166.106.63",
        "tcpPort": "4196",
        "tcpType": "DEFAULT",
        "serialPort": "/dev/ttyUSB",
        "serialType": "RTU-BUFFERD",
        "serialBaudrate": "9600",
        "serialDatabits": "8",
        "serialStopbits": "1",
        "serialParity": "none",
        "serialConnectionDelay": "100",
        "serialAsciiResponseStartDelimiter": "0x3A",
        "unit_id": "1",
        "commandDelay": "1",
        "clientTimeout": "1000",
        "reconnectOnTimeout": true,
        "reconnectTimeout": "500",
        "parallelUnitIdsAllowed": true
    }
]

```

I don't know what to do.

---

<div class="post-metadata">

**Author:** ![FrankAB](https://avatars.discourse-cdn.com/v4/letter/f/ee59a6/32.png) [@FrankAB](https://discourse.nodered.org/u/FrankAB)\
**Post date:** [6 February 2022 14:17 UTC](https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760/2 "2022-02-06T14:17:19Z")

</div>

Try to change the quantity to a lower value e.g. 4  
Are you sure unitid is 1?

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<div class="post-metadata">

**Author:** ![fernando](https://avatars.discourse-cdn.com/v4/letter/f/779978/32.png) [@fernando](https://discourse.nodered.org/u/fernando)\
**Post date:** [7 February 2022 09:43 UTC](https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760/3 "2022-02-07T09:43:10Z")

</div>

Yeah, it is.  
I configured it in Eastron device.  
I tried change quantity value too but doesn't work.

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<div class="post-metadata">

**Author:** ![FrankAB](https://avatars.discourse-cdn.com/v4/letter/f/ee59a6/32.png) [@FrankAB](https://discourse.nodered.org/u/FrankAB)\
**Post date:** [7 February 2022 20:59 UTC](https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760/4 "2022-02-07T20:59:48Z")

</div>

Waveshare - Work mode - Tcp Server

---

<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:** [8 April 2022 21:00 UTC](https://discourse.nodered.org/t/my-modbus-receives-data-but-doesnt-send-data/57760/5 "2022-04-08T21:00:42Z")

</div>

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