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LFP_Manager/Function/CsModbusFunction.cs

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+using LFP_Manager.Utils;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace LFP_Manager.Function
+{
+    internal class CsModbusFunction
+    {
+        static public byte[] MakeWriteRegisterData(ushort devId, ushort writeAddr, short[] writeData)
+        {
+            if (writeData == null || writeData.Length == 0)
+                return Array.Empty<byte>();
+
+            // 부호 확장 없이 캐스팅 (2’s complement 그대로 0..65535 범위로 들어갑니다)
+            Span<ushort> regs = writeData.Length <= 16
+                ? stackalloc ushort[writeData.Length]
+                : new ushort[writeData.Length]; // 길면 힙 사용
+
+            for (int k = 0; k < writeData.Length; k++)
+                regs[k] = unchecked((ushort)writeData[k]);
+
+            return MakeWriteRegisterData(devId, writeAddr, regs);
+        }
+        static private byte[] MakeWriteRegisterData(ushort devId, ushort writeAddr, ReadOnlySpan<ushort> writeData)
+        {
+            if (writeData.Length <= 0)
+                return Array.Empty<byte>();
+
+            const byte Func = 0x10; // PRESET_MULTI_REG
+            int regCount = writeData.Length;
+            int payloadLen = 7 + regCount * 2;     // CRC 제외 길이
+            byte[] frame = new byte[payloadLen + 2];
+
+            int i = 0;
+            frame[i++] = (byte)devId;              // Device ID
+            frame[i++] = Func;                     // Function Code (0x10)
+            frame[i++] = (byte)(writeAddr >> 8);   // Addr Hi
+            frame[i++] = (byte)writeAddr;         // Addr Lo
+            frame[i++] = (byte)(regCount >> 8);    // Count Hi
+            frame[i++] = (byte)regCount;          // Count Lo
+            frame[i++] = (byte)(regCount * 2);     // ByteCount
+
+            // 데이터: 각 레지스터를 Hi → Lo 바이트로
+            for (int j = 0; j < regCount; j++)
+            {
+                ushort v = writeData[j];
+                frame[i++] = (byte)(v >> 8);
+                frame[i++] = (byte)v;
+            }
+
+            // CRC (CRCL → CRCH) 부착
+            if (!CsCRC16.TryAppendCrcLowHigh(frame, payloadLen, 0))
+                return Array.Empty<byte>();
+
+            return frame;
+        }
+
+    }
+}