Modbus TCP Node gives Error and i don´t know why

[Kay Pohl]

Hello together,

i am using Modbus TCP Node to communicate with my Wago PLC. Everything works fine until i connect another modbus node in my flow. Here it looks like:

This is ok:

But as soon as i connect "Küche Arbeitsplatte" to "Modbus_1" i got this Error:

And i don´t know why i got this error. Can someone explain me please this error?

Thanks in advance

Kay

[steve rickus]

Kay,

I have seen this problem before -- some PLCs do not allow more than one connection (or a small number of connections) on the same port. Are both Modbus_0 and Modbus_1 using the same ip address? Depending on the PLC, you may be able to increase the number of allowed connections.

Another approach may be to set up just one connection, poll a range of addresses that includes all the ones you want to monitor, and split the results into separate values in node-red.

--

Steve

On Thursday, May 25, 2017 at 8:46:48 AM UTC-4, Kay Pohl wrote:

i am using Modbus TCP Node to communicate with my Wago PLC. Everything works fine until i connect another modbus node in my flow. Here it looks like:

[Kay Pohl]

Hi Steve,

i just looked in the PLC Manual. My PLC can handle max. 15 connections :-( 

Your approach i´ve done with Inputs. Therefore i use a function in Node Red:

var x = [0,0,0,0,0,0,0,0,0,0,0,0,0];

var msg_o = [msg,msg,msg,msg,msg,msg,msg,msg,msg,msg,msg,msg,msg];

for(i=0;i<13; i++){

    x[i] = msg.payload[i];

    if(x[i]===true){

        msg_o[i] = {payload: true};

    }else{

       msg_o[i] = {payload: false}; 

    }

}

return msg_o;

I read 13 Coils over Modbus with 1 connection and split them in a function in to 13 seperate Outputs. But i don´t know how can i do this in the other way. Make 1 array from 13 Boolean. Because function has only 1 Input right?

Kay

[steve rickus]

Kay, are you using node-red-contrib-modbustcp nodes? I have not used those, but I noticed that there is also node-red-contrib-modbustcp-no-pooling package available. I wonder if that would get around your connection issues?

My apologies, I see that you are already using one read node and splitting it into 13 msgs. I did something similar, but to avoid the big 13-output splitting node, I have a single output on my function that creates a different msg.topic for each register. I then pass the whole array of msgs to mqtt-out, and anywhere I need to listen to a specific topic, I put an mqtt-in node for that topic. So effectively it separates the reading process from the display/action processes. A similar function (using your example flow) would look something like this:

// build an array of msgs, mapping topics to registers
var msgs = [
    { topic: "Lichter/HWR", payload: msg.payload[0] },
    { topic: "Lichter/Windfang", payload: msg.payload[1] },
    { topic: "Lichter/WC", payload: msg.payload[2] },
    { topic: "Lichter/Buero", payload: msg.payload[3] },
...
    { topic: "Lichter/Flur", payload: msg.payload[12] }
];

// send the whole array of msgs to the output port
return [msgs];

Since the function is returning an array of 1 element that contains an array of 13 msg objects, the output will be 13 separate msg objects sent to MQTT. Then any other nodes/flows can subscribe to that topic and receive just that one updated value.

It looks like the outputs from all your switches could pass a msg to a single node-red-contrib-flex-write node, passing FC:5 with a start address (based on the topic) and the number of coils to be written (in your case 1, so you can just modify that one coil). I have not used it, but there are lots of warnings to use the modbus flex nodes if you have more than 10 connections.

Best of luck...

--

Steve

[Kay Pohl]

Hi Steve,

i´ve tried your function. I got on every msg.payload "undefined".

Here my Node:

[{"id":"f1f5cfe3.970f8","type":"function","z":"c02bb355.ee4ae","name":"Lichter_EG","func":"var x = [0,0,0,0,0,0,0,0,0,0,0,0,0];\nvar msg_o = [msg,msg,msg,msg,msg,msg,msg,msg,msg,msg,msg,msg,msg];\nfor(i=0;i<13; i++){\n    x[i] = msg.payload[i];\n    if(x[i]===true){\n        msg_o[i] = {payload: true};\n    }else{\n       msg_o[i] = {payload: false}; \n    }\n}\nreturn msg_o;","outputs":"13","noerr":0,"x":470,"y":240,"wires":[["8cbaabbe.1e6168"],["5128873d.aaaf38"],["53d423a2.3515bc"],["d7e93fb9.7c8bb"],["70770261.5ec5dc"],["f74d030c.0a409"],["7cce786a.fa66a8"],["76731d2.7ec2fe4"],["6bb2eae4.773bc4"],["324fee70.649e42"],["a8ce92e4.117ac"],[],[]]},{"id":"8cbaabbe.1e6168","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"HWR","group":"ad22dbee.a216c8","order":2,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"HWR","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":710,"y":40,"wires":[["edc9156c.bbd998"]]},{"id":"d7e93fb9.7c8bb","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Buero","group":"ad22dbee.a216c8","order":4,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Buero","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":710,"y":160,"wires":[["edc9156c.bbd998"]]},{"id":"e9a194bb.bee1b8","type":"comment","z":"c02bb355.ee4ae","name":"Daten von Wago PLC über Modbus auslesen","info":"","x":190,"y":40,"wires":[]},{"id":"5128873d.aaaf38","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Windfang","group":"ad22dbee.a216c8","order":1,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Windfang","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":720,"y":80,"wires":[["edc9156c.bbd998"]]},{"id":"53d423a2.3515bc","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"WC","group":"ad22dbee.a216c8","order":3,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"WC","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":710,"y":120,"wires":[["edc9156c.bbd998"]]},{"id":"70770261.5ec5dc","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Küche Mitte","group":"ad22dbee.a216c8","order":7,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Kueche_mitte","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":730,"y":200,"wires":[["edc9156c.bbd998"]]},{"id":"f74d030c.0a409","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Küche Arbeitsplatte","group":"ad22dbee.a216c8","order":6,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Kueche_arbeitsplatte","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":750,"y":240,"wires":[["edc9156c.bbd998"]]},{"id":"7cce786a.fa66a8","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Esszimmer","group":"ad22dbee.a216c8","order":8,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Esszimmer","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":730,"y":280,"wires":[["edc9156c.bbd998"]]},{"id":"76731d2.7ec2fe4","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Esszimmer Wand","group":"ad22dbee.a216c8","order":9,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Esszimmer_wand","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":750,"y":320,"wires":[["edc9156c.bbd998"]]},{"id":"6bb2eae4.773bc4","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Wohnzimmer","group":"ad22dbee.a216c8","order":10,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Wohnzimmer","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":730,"y":360,"wires":[["edc9156c.bbd998"]]},{"id":"324fee70.649e42","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Wohnzimmer Wand","group":"ad22dbee.a216c8","order":11,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Wohnzimmer_wand","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":750,"y":400,"wires":[["edc9156c.bbd998"]]},{"id":"a8ce92e4.117ac","type":"ui_switch","z":"c02bb355.ee4ae","name":"","label":"Flur","group":"ad22dbee.a216c8","order":5,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"Flur","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":710,"y":440,"wires":[["edc9156c.bbd998"]]},{"id":"6cc7af6f.b8e63","type":"modbustcp-read","z":"c02bb355.ee4ae","name":"Modbus_Lichter_EG","dataType":"Coil","adr":"17088","quantity":"13","rate":"2","rateUnit":"s","server":"c28c9bdc.97aa08","x":190,"y":240,"wires":[["f1f5cfe3.970f8"]]},{"id":"edc9156c.bbd998","type":"function","z":"c02bb355.ee4ae","name":"Lichter_EG_Write","func":"// build an array of msgs, mapping topics to registers\nvar msgs = [\n    { topic: \"HWR\", payload: msg.payload[0] },\n    { topic: \"Windfang\", payload: msg.payload[1] },\n    { topic: \"WC\", payload: msg.payload[2] },\n    { topic: \"Buero\", payload: msg.payload[3] },\n    { topic: \"Kueche_mitte\", payload: msg.payload[4] },\n    { topic: \"Kueche_arbeitsplatte\", payload: msg.payload[5] },\n    { topic: \"Esszimmer\", payload: msg.payload[6] },\n    { topic: \"Esszimmer_wand\", payload: msg.payload[7] },\n    { topic: \"Wohnzimmer\", payload: msg.payload[8] },\n    { topic: \"Wohnzimmer_wand\", payload: msg.payload[9] },\n    { topic: \"Flur\", payload: msg.payload[10] }\n];\n\n// send the whole array of msgs to the output port\nreturn [msgs];","outputs":1,"noerr":0,"x":1120,"y":240,"wires":[["127c20a7.869f4f"]]},{"id":"127c20a7.869f4f","type":"debug","z":"c02bb355.ee4ae","name":"","active":true,"console":"false","complete":"false","x":1320,"y":240,"wires":[]},{"id":"ad22dbee.a216c8","type":"ui_group","z":"","name":"Beleuchtung","tab":"7fd8e76c.53e588","order":1,"disp":true,"width":"6"},{"id":"c28c9bdc.97aa08","type":"modbustcp-server","z":"","host":"10.23.59.10","port":"502","unit_id":"1","reconnecttimeout":""},{"id":"7fd8e76c.53e588","type":"ui_tab","z":"","name":"Erdgeschoss","icon":"dashboard","order":2}]

Maybe you can look what i am doing wrong? If it works, i try to get an msg.payload with an array of 13 Registers.

Thanks in advance.

Kay

[steve rickus]

If I understand what you are trying to do, you want the payload of the modbus read to be an array of 13 register values --

this is split into 13 msg objects with each value going to a ui_switch, based on the position of the value in the array --

Then, the output of the switches need to send a msg to the plc to update the value of that specific coil, right?

What I was trying to explain was another way to replace your function with some simple core nodes, that would route the array values to their switches -- so that would be on the read side, not the write side of the flow. Something like this:

Here is the flow i mocked up (for just 4 of the switches):

[

    {

        "id": "29fb65d3.7d321a",

        "type": "tab",

        "label": "Lichter switch",

        "disabled": false,

        "info": ""

    },

    {

        "id": "573708d1.6a86d8",

        "type": "ui_switch",

        "z": "29fb65d3.7d321a",

        "name": "",

        "label": "HWR",

        "group": "8c33c2e4.11f4e",

        "order": 1,

        "width": 0,

        "height": 0,

        "passthru": true,

        "decouple": "false",

        "topic": "Lichter/HWR",

        "style": "",

        "onvalue": "1",

        "onvalueType": "str",

        "onicon": "",

        "oncolor": "",

        "offvalue": "0",

        "offvalueType": "str",

        "officon": "",

        "offcolor": "",

        "x": 410,

        "y": 280,

        "wires": [

            [

                "e647e749.22ae18",

                "e05b831f.508d1"

            ]

        ]

    },

    {

        "id": "4a060f4f.3595",

        "type": "ui_switch",

        "z": "29fb65d3.7d321a",

        "name": "",

        "label": "Buero",

        "group": "8c33c2e4.11f4e",

        "order": 4,

        "width": 0,

        "height": 0,

        "passthru": true,

        "decouple": "false",

        "topic": "Lichter/Buero",

        "style": "",

        "onvalue": "1",

        "onvalueType": "str",

        "onicon": "",

        "oncolor": "",

        "offvalue": "0",

        "offvalueType": "str",

        "officon": "",

        "offcolor": "",

        "x": 410,

        "y": 400,

        "wires": [

            [

                "e647e749.22ae18"

            ]

        ]

    },

    {

        "id": "57f56c0b.da7fb4",

        "type": "ui_switch",

        "z": "29fb65d3.7d321a",

        "name": "",

        "label": "Windfang",

        "group": "8c33c2e4.11f4e",

        "order": 2,

        "width": 0,

        "height": 0,

        "passthru": true,

        "decouple": "false",

        "topic": "Lichter/Windfang",

        "style": "",

        "onvalue": "1",

        "onvalueType": "str",

        "onicon": "",

        "oncolor": "",

        "offvalue": "0",

        "offvalueType": "str",

        "officon": "",

        "offcolor": "",

        "x": 420,

        "y": 320,

        "wires": [

            [

                "e647e749.22ae18"

            ]

        ]

    },

    {

        "id": "8b70ea34.375578",

        "type": "ui_switch",

        "z": "29fb65d3.7d321a",

        "name": "",

        "label": "WC",

        "group": "8c33c2e4.11f4e",

        "order": 3,

        "width": 0,

        "height": 0,

        "passthru": true,

        "decouple": "false",

        "topic": "Lichter/WC",

        "style": "",

        "onvalue": "1",

        "onvalueType": "str",

        "onicon": "",

        "oncolor": "",

        "offvalue": "0",

        "offvalueType": "str",

        "officon": "",

        "offcolor": "",

        "x": 410,

        "y": 360,

        "wires": [

            [

                "e647e749.22ae18"

            ]

        ]

    },

    {

        "id": "e665e232.c08b2",

        "type": "function",

        "z": "29fb65d3.7d321a",

        "name": "build coil array",

        "func": "// build an array of values from the msg.topic\nvar topics = [ \"HWR\", \"Windfang\", \"WC\", \"Buero\" ];\nvar zeros = topics.map(function (d) { return 0 });\nvar topic = msg.topic.split(\"/\")[1] || \"Unknown\";\nvar index = topics.indexOf(topic);\nif (index < 0) return null;\n\n// update the register for the incoming switch\nvar value = +msg.payload; // convert to number\nvar coils = flow.get(\"registers\") || zeros;\ncoils[index] = value;\nnode.status({ \"text\": topics[index] + (value? \" (on)\": \" (off)\") });\n\n// send the array of coil values to the output port\nmsg.payload = coils;\nreturn msg;",

        "outputs": 1,

        "noerr": 0,

        "x": 440,

        "y": 560,

        "wires": [

            [

                "9868a2f2.a3a2c"

            ]

        ]

    },

    {

        "id": "6714ada3.ab4f64",

        "type": "debug",

        "z": "29fb65d3.7d321a",

        "name": "",

        "active": true,

        "console": "false",

        "complete": "false",

        "x": 670,

        "y": 560,

        "wires": []

    },

    {

        "id": "ecb29ce0.b9b4f",

        "type": "inject",

        "z": "29fb65d3.7d321a",

        "name": "coil register values",

        "topic": "Lichter",

        "payload": "[ 0, 0, 1, 0 ]",

        "payloadType": "json",

        "repeat": "",

        "crontab": "",

        "once": false,

        "x": 190,

        "y": 120,

        "wires": [

            [

                "1726e448.7a60ec"

            ]

        ]

    },

    {

        "id": "661a5bfc.e44a74",

        "type": "comment",

        "z": "29fb65d3.7d321a",

        "name": "Read the coils and split the values by position",

        "info": "",

        "x": 270,

        "y": 60,

        "wires": []

    },

    {

        "id": "62d3f145.95a16",

        "type": "comment",

        "z": "29fb65d3.7d321a",

        "name": "Display the switches to match the coil values",

        "info": "",

        "x": 270,

        "y": 220,

        "wires": []

    },

    {

        "id": "66f04e77.72608",

        "type": "comment",

        "z": "29fb65d3.7d321a",

        "name": "Update the coils whenever any switch changes",

        "info": "",

        "x": 280,

        "y": 500,

        "wires": []

    },

    {

        "id": "1726e448.7a60ec",

        "type": "function",

        "z": "29fb65d3.7d321a",

        "name": "map coils to topics",

        "func": "// get the parent topic from the plc read node\nvar top = msg.topic || \"Lichter\";\n\n// build an array of msgs, mapping topics to registers\nvar msgs = [\n    { topic: top+\"/HWR\", payload: msg.payload[0] },\n    { topic: top+\"/Windfang\", payload: msg.payload[1] },\n    { topic: top+\"/WC\", payload: msg.payload[2] },\n    { topic: top+\"/Buero\", payload: msg.payload[3] }\n];\n\n// send the whole array of msgs to the output port\nreturn [msgs];",

        "outputs": 1,

        "noerr": 0,

        "x": 430,

        "y": 120,

        "wires": [

            [

                "48b51556.81517c",

                "52f223dc.3c445c"

            ]

        ]

    },

    {

        "id": "48b51556.81517c",

        "type": "mqtt out",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "",

        "qos": "2",

        "retain": "true",

        "broker": "ec93534d.af15b",

        "x": 650,

        "y": 120,

        "wires": []

    },

    {

        "id": "84dee794.a9eb28",

        "type": "mqtt in",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "Lichter/HWR",

        "qos": "2",

        "broker": "ec93534d.af15b",

        "x": 210,

        "y": 280,

        "wires": [

            [

                "573708d1.6a86d8"

            ]

        ]

    },

    {

        "id": "b015796e.a30e88",

        "type": "mqtt in",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "Lichter/Windfang",

        "qos": "2",

        "broker": "ec93534d.af15b",

        "x": 200,

        "y": 320,

        "wires": [

            [

                "57f56c0b.da7fb4"

            ]

        ]

    },

    {

        "id": "c9987303.1d402",

        "type": "mqtt in",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "Lichter/WC",

        "qos": "2",

        "broker": "ec93534d.af15b",

        "x": 220,

        "y": 360,

        "wires": [

            [

                "8b70ea34.375578"

            ]

        ]

    },

    {

        "id": "1c09a9f3.dc4406",

        "type": "mqtt in",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "Lichter/Buero",

        "qos": "2",

        "broker": "ec93534d.af15b",

        "x": 210,

        "y": 400,

        "wires": [

            [

                "4a060f4f.3595"

            ]

        ]

    },

    {

        "id": "e647e749.22ae18",

        "type": "mqtt out",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "",

        "qos": "2",

        "retain": "true",

        "broker": "ec93534d.af15b",

        "x": 650,

        "y": 340,

        "wires": []

    },

    {

        "id": "70a51df8.4211e4",

        "type": "mqtt in",

        "z": "29fb65d3.7d321a",

        "name": "",

        "topic": "Lichter/+",

        "qos": "2",

        "broker": "ec93534d.af15b",

        "x": 220,

        "y": 560,

        "wires": [

            [

                "e665e232.c08b2"

            ]

        ]

    },

    {

        "id": "9b1abf93.7c591",

        "type": "change",

        "z": "29fb65d3.7d321a",

        "name": "save register array",

        "rules": [

            {

                "t": "set",

                "p": "registers",

                "pt": "flow",

                "to": "payload",

                "tot": "msg"

            }

        ],

        "action": "",

        "property": "",

        "from": "",

        "to": "",

        "reg": false,

        "x": 690,

        "y": 620,

        "wires": [

            []

        ]

    },

    {

        "id": "52f223dc.3c445c",

        "type": "debug",

        "z": "29fb65d3.7d321a",

        "name": "",

        "active": true,

        "console": "false",

        "complete": "false",

        "x": 670,

        "y": 180,

        "wires": []

    },

    {

        "id": "e05b831f.508d1",

        "type": "debug",

        "z": "29fb65d3.7d321a",

        "name": "",

        "active": true,

        "console": "false",

        "complete": "false",

        "x": 670,

        "y": 280,

        "wires": []

    },

    {

        "id": "9868a2f2.a3a2c",

        "type": "delay",

        "z": "29fb65d3.7d321a",

        "name": "",

        "pauseType": "rate",

        "timeout": "5",

        "timeoutUnits": "seconds",

        "rate": "1",

        "nbRateUnits": "1",

        "rateUnits": "second",

        "randomFirst": "1",

        "randomLast": "5",

        "randomUnits": "seconds",

        "drop": true,

        "x": 450,

        "y": 620,

        "wires": [

            [

                "9b1abf93.7c591",

                "6714ada3.ab4f64"

            ]

        ]

    },

    {

        "id": "8c33c2e4.11f4e",

        "type": "ui_group",

        "z": "",

        "name": "Beleuchtung",

        "tab": "deb6edfa.18e2c",

        "order": 1,

        "disp": true,

        "width": "6"

    },

    {

        "id": "ec93534d.af15b",

        "type": "mqtt-broker",

        "z": "",

        "broker": "localhost",

        "port": "1883",

        "clientid": "",

        "usetls": false,

        "compatmode": true,

        "keepalive": "15",

        "cleansession": true,

        "willTopic": "",

        "willQos": "0",

        "willPayload": "",

        "birthTopic": "",

        "birthQos": "0",

        "birthPayload": ""

    },

    {

        "id": "deb6edfa.18e2c",

        "type": "ui_tab",

        "z": "",

        "name": "Erdgeschoss",

        "icon": "dashboard",

        "order": 2

    }

]

There is a big advantage to using MQTT to route the msgs to their respective switches (besides looking tidy!) -- whenever the flow is restarted, it receives all the retained values for each switch and updates the UI (and the flow context) with the last received values. Hope this helps...

--

Steve

On Friday, May 26, 2017 at 9:27:03 AM UTC-4, Kay Pohl wrote:

Hi Steve,

i´ve tried your function. I got on every msg.payload "undefined".

[Kay Pohl]

Hi Steve,

i can´t import your flow to mine. If i copy your flow and try to import it, nothing happens. Is there any formating problem maybe?

Kay

[Kay Pohl]

Hi Steve. It works now. I will have a look at your node.

Thanks

Kay

[Kay Pohl]

Hi Steve,

it works now. I use Modbus TCP Flex Getter instead of your MQTT Example. Thanks for your help.