Windowsで動くModbus Slaveのアプリの値を取得するフローです。
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ModbusSlaveから取得する情報としては上記のようにしました。
こうすることで、ModbusSlaveのアドレス1から10までの値を配列で取得します。
値に変化があるかチェック
ModbusSlaveのInput（FC4）の値を１秒ごとに10アドレスづつ読み込み、変化があったもののみを出力するフロー
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node.error(\"Modbusデータが配列ではありません: \" + JSON.stringify(current));\n return null;\n}\n\n// 前回値を取得\nlet before = flow.get('before_value');\n\n// -------------------------\n// 初回：全ての値を changes として出力\n// -------------------------\nif (!before) {\n let changes = [];\n\n for (let i = 0; i < current.length; i++) {\n changes.push({\n index: i,\n old: null, // 初回は old が存在しないので null\n new: current[i],\n address: i + 1\n });\n }\n\n // 初回の before を保存（deep copy）\n flow.set('before_value', JSON.parse(JSON.stringify(current)));\n\n msg.payload = {\n message: \"初回データを読み込みました\",\n changes: changes,\n timestamp: new Date().toISOString()\n };\n return msg;\n}\n\n// -------------------------\n// 2回目以降：変化チェック\n// -------------------------\nlet changes = [];\n\nfor (let i = 0; i < current.length; i++) {\n if (current[i] !== before[i]) {\n changes.push({\n index: i,\n old: before[i],\n new: current[i],\n address: i + 1\n });\n }\n}\n\n// 変化なし → 出力しない\nif (changes.length === 0) {\n return null;\n}\n\n// 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これで初回はすべて出力、その後は値に変化があったアドレスの値だけを出力します。
なので、アドレスをスイッチノードで切り分けて、操作したいデバイスの制御内容を追加することで、Inputの値によって制御することができます。