Hello,
I am trying to read and write to a s7 1200 PLC Datablock.
I have sucessfully able to read the content of DB1 which contains a array "Test" which contains 20 String variabvles. See the image.
Folowing is the json for reading
[
{
"id": "defa031d7223bc60",
"type": "s7 in",
"z": "4606f8b0d0a8d4e9",
"endpoint": "2f70a4039f09ee82",
"mode": "single",
"variable": "Andon Call Test",
"diff": false,
"name": "Andon Call Block Read",
"x": 280,
"y": 1020,
"wires": [
[
"a35cfb21a3a49967",
"3c06c3e94034441b"
]
]
},
{
"id": "78b3252143da9aad",
"type": "debug",
"z": "4606f8b0d0a8d4e9",
"name": "debug 60",
"active": true,
"tosidebar": true,
"console": false,
"tostatus": false,
"complete": "payload",
"targetType": "msg",
"statusVal": "",
"statusType": "auto",
"x": 740,
"y": 1020,
"wires": []
},
{
"id": "a35cfb21a3a49967",
"type": "function",
"z": "4606f8b0d0a8d4e9",
"name": "function 8",
"func": "const buf = msg.payload;\nconst totalStrings = 21; // Number of strings\nconst stringSize = 256; // Size of each string (padded to 256 bytes)\n\nconst parsedStrings = [];\n\nfor (let i = 0; i < totalStrings; i++) {\n const offset = i * stringSize; // Get the offset for the current string\n const actualLen = buf[offset + 1]; // Byte 1 is the actual length of the string\n\n if (actualLen > 0) {\n // Extract the byte array for the string data\n const stringBytes = buf.slice(offset + 2, offset + 2 + actualLen);\n\n // Convert the byte array into a string using ASCII encoding\n let str = '';\n for (let byte of stringBytes) {\n str += String.fromCharCode(byte);\n }\n\n parsedStrings.push(str); // Push the string into the parsedStrings array\n } else {\n parsedStrings.push(''); // Empty string if actual length is 0\n }\n}\n\nmsg.payload = parsedStrings; // Set the parsed strings as payload\nreturn msg;\n",
"outputs": 1,
"timeout": 0,
"noerr": 0,
"initialize": "",
"finalize": "",
"libs": [],
"x": 500,
"y": 1020,
"wires": [
[
"78b3252143da9aad"
]
]
},
{
"id": "3c06c3e94034441b",
"type": "debug",
"z": "4606f8b0d0a8d4e9",
"name": "debug 65",
"active": true,
"tosidebar": true,
"console": false,
"tostatus": false,
"complete": "true",
"targetType": "full",
"statusVal": "",
"statusType": "auto",
"x": 520,
"y": 980,
"wires": []
},
{
"id": "2f70a4039f09ee82",
"type": "s7 endpoint",
"transport": "iso-on-tcp",
"address": "10.243.13.61",
"port": "102",
"rack": "0",
"slot": "1",
"localtsaphi": "01",
"localtsaplo": "00",
"remotetsaphi": "01",
"remotetsaplo": "00",
"connmode": "rack-slot",
"adapter": "",
"busaddr": 2,
"cycletime": "1000",
"timeout": 2000,
"name": "",
"vartable": [
{
"addr": "DB1,B0.5375",
"name": "Andon Call Test"
},
{
"addr": "DB1,B5376.100",
"name": "Andon Call Test 1"
}
]
}
]
Now I am trying to write but Cant figure out why S7 Out node Saying
msg : error
"Error: Expected [5375] values for this item"
Incomming msg for S7 Out looks like this
msg : Objectobject
payload: buffer[5376]
[0 … 9]
0: 0x0
1: 0x13
2: 0x53
3: 0x65
4: 0x6e
5: 0x73
6: 0x6f
7: 0x72
8: 0x20
9: 0x44
[10 … 19]
10: 0x69
11: 0x73
12: 0x63
13: 0x6f
14: 0x6e
15: 0x6e
16: 0x65
17: 0x63
18: 0x74
19: 0x65
Folowing is the code
[
{
"id": "e5cb46dbef0bcd4e",
"type": "s7 out",
"z": "4606f8b0d0a8d4e9",
"endpoint": "2f70a4039f09ee82",
"variable": "Andon Call Test",
"name": "Andon Call Write",
"x": 810,
"y": 840,
"wires": []
},
{
"id": "5d183a28c9ef8549",
"type": "MSSQL",
"z": "4606f8b0d0a8d4e9",
"mssqlCN": "814fd0e4912a79ae",
"name": "LKEK1DB01",
"outField": "payload",
"returnType": "1",
"throwErrors": "0",
"query": "INSERT INTO [NodeRed].[dbo].[EventCall]\r\n (MachineID, ErrorID, UserID, RecordTime, Status, Shift, Comments, Severity)\r\nVALUES\r\n (\r\n {{payload.MachineID}},\r\n {{payload.ErrorID}},\r\n {{payload.UserID}},\r\n '{{payload.RecordTime}}',\r\n '{{payload.Status}}',\r\n '{{payload.Shift}}',\r\n '{{payload.Comments}}',\r\n '{{payload.Severity}}'\r\n )\r\n",
"modeOpt": "",
"modeOptType": "query",
"queryOpt": "payload",
"queryOptType": "msg",
"paramsOpt": "",
"paramsOptType": "none",
"rows": "rows",
"rowsType": "msg",
"parseMustache": true,
"params": [
{
"output": false,
"name": "param1",
"type": "int",
"valueType": "num",
"value": "0",
"options": {
"nullable": true,
"primary": false,
"identity": false,
"readOnly": false
}
}
],
"x": 370,
"y": 840,
"wires": [
[
"51ba80916f44af68",
"a75ed45029b6f074"
]
]
},
{
"id": "e43002f3de7f33bf",
"type": "function",
"z": "4606f8b0d0a8d4e9",
"name": "function 9",
"func": "msg.payload = `SELECT [ErrorName]\n FROM [ETD1 Andon Call System].[dbo].[ErrorType]`\n return msg;",
"outputs": 1,
"timeout": 0,
"noerr": 0,
"initialize": "",
"finalize": "",
"libs": [],
"x": 220,
"y": 840,
"wires": [
[
"5d183a28c9ef8549"
]
]
},
{
"id": "aa034cc6676389d8",
"type": "inject",
"z": "4606f8b0d0a8d4e9",
"name": "",
"props": [
{
"p": "payload"
},
{
"p": "topic",
"vt": "str"
}
],
"repeat": "",
"crontab": "",
"once": false,
"onceDelay": 0.1,
"topic": "",
"payload": "",
"payloadType": "date",
"x": 80,
"y": 840,
"wires": [
[
"e43002f3de7f33bf"
]
]
},
{
"id": "51ba80916f44af68",
"type": "debug",
"z": "4606f8b0d0a8d4e9",
"name": "debug 61",
"active": false,
"tosidebar": true,
"console": false,
"tostatus": false,
"complete": "true",
"targetType": "full",
"statusVal": "",
"statusType": "auto",
"x": 540,
"y": 800,
"wires": []
},
{
"id": "a75ed45029b6f074",
"type": "function",
"z": "4606f8b0d0a8d4e9",
"name": "function 10",
"func": "var Output = {};\nconst errorMessages = msg.payload.recordsets[0].map(item => item.ErrorName);\n\n// Config\nconst totalStrings = 21;\nconst stringSize = 256;\nconst totalSize = totalStrings * stringSize; // 5376\nconst buffer = Buffer.alloc(totalSize); // Full buffer\n\nfor (let i = 0; i < totalStrings; i++) {\n const offset = i * stringSize;\n const message = errorMessages[i] || \"\";\n const len = Math.min(message.length, stringSize - 2);\n\n buffer.writeUInt8(0, offset); // Byte 0: unused/reserved\n buffer.writeUInt8(len, offset + 1); // Byte 1: string length\n\n for (let j = 0; j < len; j++) {\n buffer.writeUInt8(message.charCodeAt(j), offset + 2 + j);\n }\n}\n\n// ✅ Send exactly 5376 bytes\nOutput.payload = buffer;\nOutput.variable = \"Andon Call\";\nreturn Output;",
"outputs": 1,
"timeout": 0,
"noerr": 0,
"initialize": "",
"finalize": "",
"libs": [],
"x": 590,
"y": 840,
"wires": [
[
"59a8b52b9686d3c9",
"e5cb46dbef0bcd4e"
]
]
},
{
"id": "59a8b52b9686d3c9",
"type": "debug",
"z": "4606f8b0d0a8d4e9",
"name": "debug 62",
"active": true,
"tosidebar": true,
"console": false,
"tostatus": false,
"complete": "true",
"targetType": "full",
"statusVal": "",
"statusType": "auto",
"x": 740,
"y": 800,
"wires": []
},
{
"id": "2f70a4039f09ee82",
"type": "s7 endpoint",
"transport": "iso-on-tcp",
"address": "10.243.13.61",
"port": "102",
"rack": "0",
"slot": "1",
"localtsaphi": "01",
"localtsaplo": "00",
"remotetsaphi": "01",
"remotetsaplo": "00",
"connmode": "rack-slot",
"adapter": "",
"busaddr": 2,
"cycletime": "1000",
"timeout": 2000,
"name": "",
"vartable": [
{
"addr": "DB1,B0.5375",
"name": "Andon Call Test"
},
{
"addr": "DB1,B5376.100",
"name": "Andon Call Test 1"
}
]
},
{
"id": "814fd0e4912a79ae",
"type": "MSSQL-CN",
"tdsVersion": "7_4",
"name": "SQL LKEK1DB01",
"server": "LKEK1DB01.CSL.LOCAL\\ETD1_ANDON_CALL",
"port": "1443",
"encyption": false,
"trustServerCertificate": true,
"database": "ETD1 Andon Call System",
"useUTC": false,
"connectTimeout": "1500",
"requestTimeout": "1500",
"cancelTimeout": "5000",
"pool": "5",
"parseJSON": false,
"enableArithAbort": true,
"readOnlyIntent": false
}
]
