# "Is Not A Valid Memory Write Message To Server"

**URL:** <https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977>\
**Category:** General\
**Tags:** modbus\
**Created:** [27 April 2023 11:10 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977 "2023-04-27T11:10:06Z")\
**Posts on this page:** 10\
**Page:** 1

<div class="post-metadata">

**Author:** ![Darren](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/darren/32/92202_2.png) [@Darren](https://discourse.nodered.org/u/Darren)\
**Post date:** [27 April 2023 11:10 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/1 "2023-04-27T11:10:06Z")

</div>

I'm getting a bunch of numbers via Modbus TCP and am looking to rebroadcast those numbers via a node-red Modbus server, as below. However, I keep getting `"Is Not A Valid Memory Write Message To Server"` in the debug log on inputting these numbers. Related to [this issue](https://discourse.nodered.org/t/questions-about-modbus-ui-controls-and-forwarding-signals/777380). Also for some reason the payload buffer is 48, despite only having 6 each of coils, holdings, inputs and discretes (24 total?)

```auto
[
    {
        "id": "5d59c82badda5237",
        "type": "modbus-server",
        "z": "37f1be47da815ae1",
        "name": "",
        "logEnabled": true,
        "hostname": "0.0.0.0",
        "serverPort": 10502,
        "responseDelay": 100,
        "delayUnit": "ms",
        "coilsBufferSize": "6",
        "holdingBufferSize": "6",
        "inputBufferSize": "6",
        "discreteBufferSize": "6",
        "showErrors": true,
        "x": 1520,
        "y": 1240,
        "wires": [
            [
                "d04855631aecc823"
            ],
            [],
            [],
            [],
            []
        ]
    },
    {
        "id": "f5457920917eb0f0",
        "type": "switch",
        "z": "37f1be47da815ae1",
        "name": "",
        "property": "topic",
        "propertyType": "msg",
        "rules": [
            {
                "t": "eq",
                "v": "gboiler_running_condition",
                "vt": "str"
            },
            {
                "t": "eq",
                "v": "gsilo_level_0_1000",
                "vt": "str"
            },
            {
                "t": "eq",
                "v": "gmax_stoker_speed",
                "vt": "str"
            },
            {
                "t": "eq",
                "v": "gpid_stoker_output",
                "vt": "str"
            }
        ],
        "checkall": "true",
        "repair": false,
        "outputs": 4,
        "x": 990,
        "y": 1040,
        "wires": [
            [
                "c396898e828dee2a"
            ],
            [
                "4cefa7be49623107"
            ],
            [
                "8512686ef7c21c3e"
            ],
            [
                "62340306b6eaf6f0"
            ]
        ]
    },
    {
        "id": "b3fc5514304b5242",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "name": "Boiler Heat Meter kW & mWh [req. Serial RS485]",
        "info": "",
        "x": 200,
        "y": 960,
        "wires": []
    },
    {
        "id": "290109b199a881e3",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "name": "Get Silo Level",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gsilo_level_0_1000",
        "payload": "",
        "payloadType": "date",
        "x": 140,
        "y": 1020,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "889f040436167658",
        "type": "link out",
        "z": "37f1be47da815ae1",
        "name": "Sensors out",
        "mode": "link",
        "links": [
            "37db5198429b7396"
        ],
        "x": 405,
        "y": 1040,
        "wires": []
    },
    {
        "id": "99eb4635c1919a85",
        "type": "link in",
        "z": "37f1be47da815ae1",
        "name": "Processor in",
        "links": [
            "da25e4e66d04561c"
        ],
        "x": 705,
        "y": 1040,
        "wires": [
            [
                "134c7774ebcf3011"
            ]
        ]
    },
    {
        "id": "134c7774ebcf3011",
        "type": "modbus-flex-getter",
        "z": "37f1be47da815ae1",
        "name": "Boiler_getter",
        "showStatusActivities": false,
        "showErrors": false,
        "showWarnings": true,
        "logIOActivities": false,
        "server": "d8b07ddb.c44d4",
        "useIOFile": false,
        "ioFile": "",
        "useIOForPayload": false,
        "emptyMsgOnFail": false,
        "keepMsgProperties": false,
        "delayOnStart": false,
        "startDelayTime": "",
        "x": 830,
        "y": 1040,
        "wires": [
            [
                "f5457920917eb0f0"
            ],
            []
        ]
    },
    {
        "id": "4486d6e85a7d3e1b",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "name": "<-- I/O through lvc_labels -->",
        "info": "",
        "x": 560,
        "y": 1040,
        "wires": []
    },
    {
        "id": "85ebfdbffa8d984b",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "name": "debug 10",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "payload",
        "targetType": "msg",
        "statusVal": "",
        "statusType": "auto",
        "x": 1480,
        "y": 980,
        "wires": []
    },
    {
        "id": "a28bbddf98fa5939",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "name": "Shutdown/Fireout",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gboiler_running_condition",
        "payload": "",
        "payloadType": "date",
        "x": 150,
        "y": 900,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "4f9540eaeb13509a",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "name": "Stoker at maximum speed",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gmax_stoker_speed",
        "payload": "",
        "payloadType": "date",
        "x": 160,
        "y": 1140,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "ad73abc4d0bad61d",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "name": "Averaged stoker speed",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gpid_stoker_output",
        "payload": "",
        "payloadType": "date",
        "x": 150,
        "y": 1220,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "c396898e828dee2a",
        "type": "function",
        "z": "37f1be47da815ae1",
        "name": "Shutdown/Fireout scale",
        "func": "msg.payload = msg.payload[0]/1;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1210,
        "y": 980,
        "wires": [
            [
                "85ebfdbffa8d984b",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "4cefa7be49623107",
        "type": "function",
        "z": "37f1be47da815ae1",
        "name": "Silo Level scale",
        "func": "msg.payload = msg.payload/10.0;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1180,
        "y": 1020,
        "wires": [
            [
                "8916057c5b4e9270",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "8512686ef7c21c3e",
        "type": "function",
        "z": "37f1be47da815ae1",
        "name": "Maximum stoker speed scale",
        "func": "msg.payload = msg.payload/1;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1220,
        "y": 1060,
        "wires": [
            [
                "ed36434616147015",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "62340306b6eaf6f0",
        "type": "function",
        "z": "37f1be47da815ae1",
        "name": "Averaged stoker speed scale",
        "func": "msg.payload = msg.payload/1;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1220,
        "y": 1100,
        "wires": [
            [
                "248c46681d071246",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "c5a0fdf6b8bb9850",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "name": "[Unavailable] Stoker at minimum speed",
        "info": "",
        "x": 170,
        "y": 1080,
        "wires": []
    },
    {
        "id": "8916057c5b4e9270",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "name": "debug 11",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1480,
        "y": 1020,
        "wires": []
    },
    {
        "id": "ed36434616147015",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "name": "debug 12",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1480,
        "y": 1060,
        "wires": []
    },
    {
        "id": "248c46681d071246",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "name": "debug 13",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1480,
        "y": 1100,
        "wires": []
    },
    {
        "id": "d04855631aecc823",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "name": "Server output",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 1760,
        "y": 780,
        "wires": []
    },
    {
        "id": "d8b07ddb.c44d4",
        "type": "modbus-client",
        "name": "Boiler_PLC",
        "clienttype": "tcp",
        "bufferCommands": true,
        "stateLogEnabled": false,
        "queueLogEnabled": false,
        "failureLogEnabled": false,
        "tcpHost": "192.168.127.2",
        "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": "1000",
        "reconnectOnTimeout": true,
        "reconnectTimeout": "2000",
        "parallelUnitIdsAllowed": true
    }
]

```

Debug log output:

```auto
Is Not A Valid Memory Write Message To Server

```

alternating with

```auto
{"type":"holding","message":{"topic":"gsilo_level_0_1000","messageId":"644ac6d20671dce7f47d76ac","payload":70.2,"queueLengthByUnitId":{"unitId":255,"queueLength":2},"queueUnitId":255,"unitId":255,"modbusRequest":{"unitid":255,"fc":3,"address":105,"quantity":1,"emptyMsgOnFail":false,"keepMsgProperties":false,"messageId":"644ac6d20671dce7f47d76ac"},"responseBuffer":{"data":[702],"buffer":[2,190]},"_msgid":"649dc0709a39ce6f"},"payload":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"_msgid":"5d77a44cfc59b6dd"}

```

---

<div class="post-metadata">

**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [27 April 2023 11:22 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/2 "2023-04-27T11:22:38Z")

</div>

> [@Darren](#):
>
> Related to [this issue](https://discourse.nodered.org/t/questions-about-modbus-ui-controls-and-forwarding-signals/777380).

Your link does not work.

---

<div class="post-metadata">

**Author:** ![Darren](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/darren/32/92202_2.png) [@Darren](https://discourse.nodered.org/u/Darren)\
**Post date:** [27 April 2023 11:55 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/3 "2023-04-27T11:55:32Z")

</div>

Oops, sorry - I must have copied it wrong: [Questions about Modbus - UI controls and forwarding signals?](https://discourse.nodered.org/t/questions-about-modbus-ui-controls-and-forwarding-signals/77738)

---

<div class="post-metadata">

**Author:** ![Darren](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/darren/32/92202_2.png) [@Darren](https://discourse.nodered.org/u/Darren)\
**Post date:** [3 May 2023 09:11 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/4 "2023-05-03T09:11:54Z")

</div>

The original titular error message has now mysteriously disappeared with flow tidying my end; I suspect it may have been some malfunctioning experiment's output.

* * *

Now I'm getting a different error message:

```auto
"TypeError: Cannot read properties of undefined (reading 'length')"

```

Can anyone help?

---

<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:** [3 May 2023 10:01 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/5 "2023-05-03T10:01:16Z")

</div>

Which node is throwing that error?

---

<div class="post-metadata">

**Author:** ![Darren](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/darren/32/92202_2.png) [@Darren](https://discourse.nodered.org/u/Darren)\
**Post date:** [3 May 2023 10:09 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/6 "2023-05-03T10:09:11Z")

</div>

> [@Darren](#):
>
> `"TypeError: Cannot read properties of undefined (reading 'length')"`

Seems to be the fireout node, which is giving `value: undefined`. Not sure why, as it's setup more or less the same as the other nodes. It will give different values depending on the power state, System Stopped/Loading/Starting/Running/Temperature/Stopping. Here's the annotated flow:

```auto
[
    {
        "id": "3decb5f518882686",
        "type": "subflow",
        "name": "live debug",
        "info": "",
        "category": "",
        "in": [
            {
                "x": 240,
                "y": 160,
                "wires": [
                    {
                        "id": "45dbf990.ba2408"
                    }
                ]
            }
        ],
        "out": [
            {
                "x": 560,
                "y": 160,
                "wires": [
                    {
                        "id": "45dbf990.ba2408",
                        "port": 1
                    }
                ]
            }
        ],
        "env": [
            {
                "name": "debug_name",
                "type": "str",
                "value": "Debug",
                "ui": {
                    "label": {
                        "en-US": "Name"
                    },
                    "type": "input",
                    "opts": {
                        "types": [
                            "str"
                        ]
                    }
                }
            },
            {
                "name": "debug_property",
                "type": "str",
                "value": "msg",
                "ui": {
                    "label": {
                        "en-US": "Property Path"
                    },
                    "type": "input",
                    "opts": {
                        "types": [
                            "str"
                        ]
                    }
                }
            },
            {
                "name": "pass_debug_property",
                "type": "bool",
                "value": "false",
                "ui": {
                    "label": {
                        "en-US": "Pass Property Path"
                    },
                    "type": "input",
                    "opts": {
                        "types": [
                            "bool"
                        ]
                    }
                }
            }
        ],
        "meta": {},
        "color": "#DDAA99"
    },
    {
        "id": "45dbf990.ba2408",
        "type": "function",
        "z": "3decb5f518882686",
        "name": "format time nicely",
        "func": "let msg1 = {payload: RED.util.cloneMessage(msg)};\nmsg1.payload.debug_property = msg.debug_property || env.get(\"debug_property\") || \"msg\"\ntry {\n msg1.payload.debug_property_array = RED.util.normalisePropertyExpression(msg1.payload.debug_property)\n}\ncatch(error){\n msg.payload = error;\n msg1.payload.error = error;\n}\nmsg1.payload.debug_name = env.get(\"debug_name\") || msg._msgid || \"name error\"\nmsg1.payload.pass_debug_property = env.get(\"pass_debug_property\") || false\nreturn [msg1,msg];",
        "outputs": 2,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 390,
        "y": 120,
        "wires": [
            [
                "50da04b3.af25fc"
            ],
            []
        ]
    },
    {
        "id": "50da04b3.af25fc",
        "type": "websocket out",
        "z": "3decb5f518882686",
        "name": "",
        "server": "985ecbc7.67a138",
        "client": "",
        "x": 680,
        "y": 120,
        "wires": []
    },
    {
        "id": "1787be40.e87842",
        "type": "http in",
        "z": "3decb5f518882686",
        "name": "",
        "url": "/debug",
        "method": "get",
        "upload": false,
        "swaggerDoc": "",
        "x": 330,
        "y": 40,
        "wires": [
            [
                "1857548e.e7a8ab"
            ]
        ]
    },
    {
        "id": "1857548e.e7a8ab",
        "type": "template",
        "z": "3decb5f518882686",
        "name": "Simple Web Page",
        "field": "payload",
        "fieldType": "msg",
        "format": "html",
        "syntax": "mustache",
        "template": "<!DOCTYPE HTML>\n<html>\n <head>\n <style>\n span.debug_name {\n color: black;\n }\n span.debug_error{\n color: red;\n }\n span.debug_date{\n color:blue;\n }\n pre[id^='json_data_']{\n font-size:20px;\n background-color: ghostwhite;\n border: 1px solid silver;\n padding: 10px 20px;\n margin: 20px; \n white-space: pre-wrap;\n }\n .json-key {\n color: olive;\n }\n .json-value {\n color: navy;\n }\n .json-string {\n color: brown;\n }\n\n </style>\n <title>Debug Messages</title>\n <script type=\"text/javascript\">\n var ws;\n var wsUri = \"ws:\";\n var loc = window.location;\n console.log(loc);\n if (loc.protocol === \"https:\") { wsUri = \"wss:\"; }\n // This needs to point to the web socket in the Node-RED flow\n wsUri += \"//\" + loc.host + loc.pathname.replace(\"debug\",\"ws/debug\");\n\n function wsConnect() {\n console.log(\"connect\",wsUri);\n ws = new WebSocket(wsUri);\n ws.onmessage = function(msg) {\n segments = document.getElementById('json_data').innerHTML;\n var paused = document.getElementById('paused').innerText === \"Pause\";\n var data;\n var line = \"\";\n var error = \"\";\n var date = new Date().toISOString();\n // parse the incoming message as a JSON object\n try { \n data = JSON.parse(msg.data);\n } catch (json_error) {\n data = {error: [\"json parse error\", json_error]};\n }; \n if(!data.error){\n var debug_name = data.debug_name ;\n var debug_property = data.debug_property_array;\n var original_property = data.debug_property;\n if(!data.pass_debug_property) delete data.debug_property;\n delete data.pass_debug_property;\n delete data.debug_property_array;\n delete data.debug_name;\n debug_property.slice(1).forEach((prop, index) => {\n if(data[prop]) { \n data = data[prop];\n }else{\n error = \"Property path Error on or after - \" + debug_property[index];\n }\n });\n\n line = `<div id=\"element${date}\">\n <hr/>\n <span class=\"debug_name\">${debug_name}</span> <span class=\"debug_date\">${date}</span> \n <span class=\"debug_orginal\">${original_property}</span> <span class=\"debug_error\">${error}</span> \n <button title=\"copy\" alt=\"copy\" onclick=\"copy_text('json_data_${date}')\"> &#10066; </button>\n <button title=\"delete\" alt=\"delete\" onclick=\"delete_text('element${date}')\"> &#10060; </button> \n <span class=\"json_data\">\n <pre id=\"json_data_${date}\"><code id=data>${library.json.prettyPrint(data)}</code></pre></span> \n </div>`;\n }else{\n line = `<div id=\"element${date}\">\n <hr/>\n <span class=\"debug_error\">Error: ${JSON.stringify(data.error)}</span> <span class=\"debug_date\">${date}</span> \n <button title=\"delete\" alt=\"delete\" onclick=\"delete_text('element${date}')\"> &#10060; </button> \n </div>`;\n }\n // append line to segment\n if(paused){\n document.getElementById('json_data').innerHTML = line + segments;\n }\n }\n ws.onopen = function() {\n // update the status div with the connection status\n document.getElementById('status').innerHTML = \"connected\";\n //ws.send(\"Open for data\");\n console.log(\"connected\");\n }\n ws.onclose = function() {\n // update the status div with the connection status\n document.getElementById('status').innerHTML = \"not connected\";\n // in case of lost connection tries to reconnect every 3 secs\n setTimeout(wsConnect,3000);\n }\n }\n function copy_text(input) {\n // Get the text field\n var copyText = document.getElementById(input).innerText;\n var dummy = document.createElement(\"textarea\");\n document.body.appendChild(dummy);\n dummy.value = copyText;\n dummy.select();\n document.execCommand(\"copy\");\n document.body.removeChild(dummy);\n alert(\"Copied Data to Clipboard\\n\\n\" + copyText)\n }\n function delete_text(input) {\n // Get the text field\n document.getElementById(input).innerHTML = \"\";\n }\n if (!library) var library = {};\n library.json = {\n replacer: function(match, pIndent, pKey, pVal, pEnd) {\n var key = '<span class=json-key>\"';\n var val = '<span class=json-value>';\n var str = '<span class=json-string>';\n var r = pIndent || '';\n if (pKey)\n r = r + key + pKey.replace(/[\":]/g, '') + '\"</span>: ';\n if (pVal)\n r = r + (pVal[0] == '\"' ? str : val) + pVal + '</span>';\n return r + (pEnd || '');\n },\n prettyPrint: function(obj) {\n var jsonLine = /^( *)(\"[\\w]+\": )?(\"[^\"]*\"|[\\w.+-]*)?([,[{])?$/mg;\n return JSON.stringify(obj, null, 4)\n .replace(/&/g, '&amp;').replace(/\\\\\"/g, '&quot;')\n .replace(/</g, '&lt;').replace(/>/g, '&gt;')\n .replace(jsonLine, library.json.replacer);\n }\n \n };\n function pause() {\n var element_paused = document.getElementById(\"paused\");\n paused = (element_paused.innerText === \"Resume\") ? \"Pause\" : \"Resume\";\n element_paused.innerText = paused;\n }\n \n </script>\n </head>\n <body onload=\"wsConnect();\" onunload=\"ws.disconnect();\">\n <font face=\"Arial\">\n <h1>Debug Messages <button id=\"paused\" value=\"pause\" onclick=\"pause()\">Pause</button> </h1>\n <div id=\"json_data\"></div>\n <hr/>\n <div id=\"status\">unknown</div>\n </font>\n </body>\n</html>\n",
        "x": 550,
        "y": 40,
        "wires": [
            [
                "42a28745.bd5d78"
            ]
        ]
    },
    {
        "id": "42a28745.bd5d78",
        "type": "http response",
        "z": "3decb5f518882686",
        "name": "",
        "x": 730,
        "y": 40,
        "wires": []
    },
    {
        "id": "985ecbc7.67a138",
        "type": "websocket-listener",
        "z": "37f1be47da815ae1",
        "path": "/ws/debug",
        "wholemsg": "false"
    },
    {
        "id": "37f1be47da815ae1",
        "type": "tab",
        "label": "Modbus Server",
        "disabled": false,
        "info": "",
        "env": []
    },
    {
        "id": "49c18e3ad19acbda",
        "type": "group",
        "z": "37f1be47da815ae1",
        "style": {
            "stroke": "#999999",
            "stroke-opacity": "1",
            "fill": "none",
            "fill-opacity": "1",
            "label": true,
            "label-position": "nw",
            "color": "#a4a4a4"
        },
        "nodes": [
            "c5a0fdf6b8bb9850",
            "ed36434616147015",
            "248c46681d071246",
            "62340306b6eaf6f0",
            "f5457920917eb0f0",
            "8512686ef7c21c3e",
            "4cefa7be49623107",
            "c396898e828dee2a",
            "85ebfdbffa8d984b",
            "8916057c5b4e9270",
            "5d59c82badda5237",
            "d04855631aecc823",
            "3acabffc83517f90",
            "134c7774ebcf3011",
            "4486d6e85a7d3e1b",
            "889f040436167658",
            "99eb4635c1919a85",
            "b3fc5514304b5242",
            "a28bbddf98fa5939",
            "290109b199a881e3",
            "4f9540eaeb13509a",
            "ad73abc4d0bad61d"
        ],
        "x": 14,
        "y": 159,
        "w": 1932,
        "h": 444.5
    },
    {
        "id": "5d59c82badda5237",
        "type": "modbus-server",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "",
        "logEnabled": true,
        "hostname": "0.0.0.0",
        "serverPort": 10502,
        "responseDelay": 100,
        "delayUnit": "ms",
        "coilsBufferSize": "6",
        "holdingBufferSize": "6",
        "inputBufferSize": "6",
        "discreteBufferSize": "6",
        "showErrors": true,
        "x": 1560,
        "y": 540,
        "wires": [
            [
                "d04855631aecc823",
                "3acabffc83517f90"
            ],
            [],
            [],
            [],
            []
        ]
    },
    {
        "id": "d04855631aecc823",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Server output",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 1820,
        "y": 440,
        "wires": []
    },
    {
        "id": "f5457920917eb0f0",
        "type": "switch",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "",
        "property": "topic",
        "propertyType": "msg",
        "rules": [
            {
                "t": "eq",
                "v": "gboiler_running_condition",
                "vt": "str"
            },
            {
                "t": "eq",
                "v": "gsilo_level_0_1000",
                "vt": "str"
            },
            {
                "t": "eq",
                "v": "gmax_stoker_speed",
                "vt": "str"
            },
            {
                "t": "eq",
                "v": "gpid_stoker_output",
                "vt": "str"
            }
        ],
        "checkall": "true",
        "repair": false,
        "outputs": 4,
        "x": 1030,
        "y": 340,
        "wires": [
            [
                "c396898e828dee2a"
            ],
            [
                "4cefa7be49623107"
            ],
            [
                "8512686ef7c21c3e"
            ],
            [
                "62340306b6eaf6f0"
            ]
        ]
    },
    {
        "id": "b3fc5514304b5242",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Boiler Heat Meter kW & mWh [req. Serial RS485]",
        "info": "",
        "x": 240,
        "y": 260,
        "wires": []
    },
    {
        "id": "290109b199a881e3",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Get Silo Level",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gsilo_level_0_1000",
        "payload": "",
        "payloadType": "date",
        "x": 180,
        "y": 320,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "889f040436167658",
        "type": "link out",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Sensors out",
        "mode": "link",
        "links": [
            "37db5198429b7396"
        ],
        "x": 445,
        "y": 340,
        "wires": []
    },
    {
        "id": "99eb4635c1919a85",
        "type": "link in",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Processor in",
        "links": [
            "da25e4e66d04561c"
        ],
        "x": 745,
        "y": 340,
        "wires": [
            [
                "134c7774ebcf3011"
            ]
        ]
    },
    {
        "id": "134c7774ebcf3011",
        "type": "modbus-flex-getter",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Boiler_getter",
        "showStatusActivities": false,
        "showErrors": false,
        "showWarnings": true,
        "logIOActivities": false,
        "server": "d8b07ddb.c44d4",
        "useIOFile": false,
        "ioFile": "",
        "useIOForPayload": false,
        "emptyMsgOnFail": false,
        "keepMsgProperties": false,
        "delayOnStart": false,
        "startDelayTime": "",
        "x": 870,
        "y": 340,
        "wires": [
            [
                "f5457920917eb0f0"
            ],
            []
        ]
    },
    {
        "id": "4486d6e85a7d3e1b",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "<-- I/O through lvc_labels -->",
        "info": "",
        "x": 600,
        "y": 340,
        "wires": []
    },
    {
        "id": "85ebfdbffa8d984b",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "debug 10",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "payload",
        "targetType": "msg",
        "statusVal": "",
        "statusType": "auto",
        "x": 1520,
        "y": 280,
        "wires": []
    },
    {
        "id": "a28bbddf98fa5939",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Shutdown/Fireout",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gboiler_running_condition",
        "payload": "",
        "payloadType": "date",
        "x": 190,
        "y": 200,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "4f9540eaeb13509a",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Stoker at maximum speed",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gmax_stoker_speed",
        "payload": "",
        "payloadType": "date",
        "x": 200,
        "y": 440,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "ad73abc4d0bad61d",
        "type": "inject",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Averaged stoker speed",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "5",
        "crontab": "",
        "once": true,
        "onceDelay": "1",
        "topic": "gpid_stoker_output",
        "payload": "",
        "payloadType": "date",
        "x": 190,
        "y": 520,
        "wires": [
            [
                "889f040436167658"
            ]
        ]
    },
    {
        "id": "c396898e828dee2a",
        "type": "function",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "[ERROR] Shutdown/Fireout scale",
        "func": "// This node causes \"TypeError: Cannot read properties of undefined (reading 'length')\"\nmsg.payload = msg.payload[0]/1;\n\nmsg.payload = { 'value': msg.payload[0],\n 'register': 'holding',\n 'address': 1,\n 'disableMsgOutput': 0 };\n \n return msg;\n",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1280,
        "y": 280,
        "wires": [
            [
                "85ebfdbffa8d984b"
            ]
        ]
    },
    {
        "id": "4cefa7be49623107",
        "type": "function",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Silo Level scale",
        "func": "msg.payload = {\n 'value': msg.payload,\n 'register': 'holding',\n 'address': 2,\n 'disableMsgOutput': 0\n};\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1220,
        "y": 320,
        "wires": [
            [
                "8916057c5b4e9270",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "8512686ef7c21c3e",
        "type": "function",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Maximum stoker speed scale",
        "func": "msg.payload = {\n 'value': msg.payload,\n 'register': 'holding',\n 'address': 3,\n 'disableMsgOutput': 0\n};\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1260,
        "y": 360,
        "wires": [
            [
                "ed36434616147015",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "62340306b6eaf6f0",
        "type": "function",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "Averaged stoker speed scale",
        "func": "msg.payload = {\n 'value': msg.payload,\n 'register': 'holding',\n 'address': 4,\n 'disableMsgOutput': 0\n};\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1260,
        "y": 400,
        "wires": [
            [
                "248c46681d071246",
                "5d59c82badda5237"
            ]
        ]
    },
    {
        "id": "c5a0fdf6b8bb9850",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "[Unavailable] Stoker at minimum speed",
        "info": "",
        "x": 190,
        "y": 380,
        "wires": []
    },
    {
        "id": "8916057c5b4e9270",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "debug 11",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1520,
        "y": 320,
        "wires": []
    },
    {
        "id": "ed36434616147015",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "debug 12",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1500,
        "y": 360,
        "wires": []
    },
    {
        "id": "248c46681d071246",
        "type": "debug",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "debug 13",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 1500,
        "y": 400,
        "wires": []
    },
    {
        "id": "3acabffc83517f90",
        "type": "subflow:3decb5f518882686",
        "z": "37f1be47da815ae1",
        "g": "49c18e3ad19acbda",
        "name": "",
        "x": 1830,
        "y": 540,
        "wires": [
            []
        ]
    },
    {
        "id": "c1f1279b6bad34ee",
        "type": "comment",
        "z": "37f1be47da815ae1",
        "name": "Brown & Carroll Modbus re-server",
        "info": "",
        "x": 920,
        "y": 100,
        "wires": []
    },
    {
        "id": "d8b07ddb.c44d4",
        "type": "modbus-client",
        "name": "Boiler_PLC",
        "clienttype": "tcp",
        "bufferCommands": true,
        "stateLogEnabled": false,
        "queueLogEnabled": false,
        "failureLogEnabled": false,
        "tcpHost": "192.168.127.2",
        "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": "1000",
        "reconnectOnTimeout": true,
        "reconnectTimeout": "2000",
        "parallelUnitIdsAllowed": true
    }
]

```

---

<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:** [3 May 2023 10:17 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/7 "2023-05-03T10:17:30Z")

</div>

> [@Darren](#):
>
> Seems to be the fireout node

You have this code in that function

```auto
msg.payload = msg.payload[0]/1;
msg.payload = { 'value': msg.payload[0],

```

The first line sets msg.payload to whatever is in msg.payload[0], though I don't know why you are dividing it by 1. After that line is executed msg.payload is no longer an array. In the second line you are trying to pick up msg.payload[0] again, but it is no longer an array. Perhaps you meant  
`msg.payload = {value: msg.payload, `  
If the purpose of dividing by 1 is to convert it from a string to a number then you can remove the first line, and in the second line use  
`msg.payload = { 'value': Number(msg.payload[0]), `

---

<div class="post-metadata">

**Author:** ![Darren](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/darren/32/92202_2.png) [@Darren](https://discourse.nodered.org/u/Darren)\
**Post date:** [3 May 2023 10:23 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/8 "2023-05-03T10:23:37Z")

</div>

That seems to have fixed it; thank you so much!

The division by 1 is a mysterious artifact inherited from legacy code; your archaeology skills are much better than mine, and your interpretation makes sense as well as banishing the error I was having.

---

<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:** [3 May 2023 10:56 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/9 "2023-05-03T10:56:12Z")

</div>

By the way, in javascript, if object properties do not contain special characters such as - or space then you don't need to include them in quotes, so you could save a bit of typing and use

```auto
msg.payload = {value: Number(msg.payload[0]),
  register: 'holding',
  address: 1,
  disableMsgOutput: 0
};

```

If you are writing JSON then you do need the quotes.

---

<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:** [17 May 2023 10:56 UTC](https://discourse.nodered.org/t/is-not-a-valid-memory-write-message-to-server/77977/10 "2023-05-17T10:56:42Z")

</div>

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.