From d78c1a0573fba172c3bf89abd38e4cace3ed2050 Mon Sep 17 00:00:00 2001 From: Fuyao Date: Mon, 17 Nov 2025 18:26:04 +0800 Subject: [PATCH 1/2] =?UTF-8?q?=E5=AE=8C=E5=96=84=E8=87=AA=E5=AE=9A?= =?UTF-8?q?=E4=B9=89=E6=95=B0=E6=8D=AE=E8=AF=BB=E5=8F=96?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- rtu_transport.go | 101 +++++++++++++++++++++++++++++++---------------- 1 file changed, 66 insertions(+), 35 deletions(-) diff --git a/rtu_transport.go b/rtu_transport.go index 0f29a70..11bcaaf 100644 --- a/rtu_transport.go +++ b/rtu_transport.go @@ -80,7 +80,9 @@ func (rt *rtuTransport) ExecuteRequest(req *pdu) (res *pdu, err error) { // build an RTU ADU out of the request object and // send the final ADU+CRC on the wire n, err = rt.link.Write(rt.assembleRTUFrame(req)) + fmt.Printf("send: %X\n", rt.assembleRTUFrame(req)) if err != nil { + fmt.Printf("write error: %s", err.Error()) return } @@ -193,7 +195,7 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { var byteCount int var bytesNeeded int var crc crc - var dataLength uint16 + // var dataLength uint16 rxbuf = make([]byte, maxRTUFrameLength) @@ -204,6 +206,9 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { err = ErrShortFrame return } + if uint8(rxbuf[1]) == fcCustomize { + fmt.Printf("receive: %v\n", rxbuf[0:3]) + } if err != nil && err != io.ErrUnexpectedEOF { return } @@ -211,64 +216,90 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { // handle custom function code 0x41 with special format: // [单元ID] [功能码] [起始地址(2字节)] [字节数(2字节)] [数据...] [CRC] if uint8(rxbuf[1]) == fcCustomize { - // read the start address (2 bytes) and byte count (2 bytes) - byteCount, err = io.ReadFull(rt.link, rxbuf[3:7]) - if (byteCount > 0 || err == nil) && byteCount != 4 { - err = ErrShortFrame - return - } - if err != nil && err != io.ErrUnexpectedEOF { - return - } + // 1. 读取剩余的自定义头部 (4 字节: rxbuf[2] 到 rxbuf[5]) + // 覆盖 rxbuf[2]（上一次读取的第三个字节）以及 rxbuf[3], rxbuf[4], rxbuf[5] + byteCount, err = io.ReadFull(rt.link, rxbuf[3:6]) // <-- 关键修正：从索引 2 开始读取 4 字节 - // extract data length from bytes 5-6 (byte count field, big endian) - dataLength = bytesToUint16(BIG_ENDIAN, rxbuf[5:7]) + // 修正短帧检查逻辑 + if err != nil { + if err == io.EOF || err == io.ErrUnexpectedEOF { + err = ErrShortFrame + } + return + } + // 此时 byteCount 应该总是 4。 + + // 2. 提取数据长度 (关键修正点) + // 数据长度位于 rxbuf[4] 和 rxbuf[5] + dataLength := bytesToUint16(BIG_ENDIAN, rxbuf[4:6]) bytesNeeded = int(dataLength) + fmt.Println(bytesNeeded) - // we need to read 2 additional bytes of CRC after the payload - bytesNeeded += 2 + // 3. 计算总共需要读取的字节数 + // 数据域长度 + 2 字节 CRC + bytesToRead := bytesNeeded + 2 - // calculate total frame size: 3 (header) + 4 (start addr + byte count) + data + 2 (CRC) - totalFrameSize := 7 + bytesNeeded + // 4. 计算总帧大小: 6 (Header) + DataLength + 2 (CRC) + totalFrameSize := 6 + bytesToRead + TotalHeaderLength := 6 - // for custom function code, we may need a larger buffer than maxRTUFrameLength - // allocate buffer dynamically if needed + // 5. 动态分配或调整缓冲区 if totalFrameSize > maxRTUFrameLength { // save already read data - header := make([]byte, 7) - copy(header, rxbuf[0:7]) + header := make([]byte, 6) + copy(header, rxbuf[0:TotalHeaderLength]) // 复制 rxbuf[0] 到 rxbuf[5] + // resize buffer to accommodate larger frame rxbuf = make([]byte, totalFrameSize) + // copy back the header - copy(rxbuf[0:7], header) + copy(rxbuf[0:TotalHeaderLength], header) } - // read the data and CRC - byteCount, err = io.ReadFull(rt.link, rxbuf[7:7+bytesNeeded]) - if err != nil && err != io.ErrUnexpectedEOF { + // 6. 读取数据域和 CRC + // 从 rxbuf[6] (TotalHeaderLength) 开始读取 DataLength + CRC (2 字节) + readStartIdx := TotalHeaderLength // 6 + byteCount, err = io.ReadFull(rt.link, rxbuf[readStartIdx:totalFrameSize]) + + if err != nil { + if err == io.EOF || err == io.ErrUnexpectedEOF { + err = ErrShortFrame + } return } - if byteCount != bytesNeeded { - rt.logger.Warningf("expected %v bytes, received %v", bytesNeeded, byteCount) + + if byteCount != bytesToRead { + rt.logger.Warningf("expected %v bytes, received %v", bytesToRead, byteCount) err = ErrShortFrame return } - // compute the CRC on the entire frame, excluding the CRC + // 7. CRC 校验 + crcEndIndex := totalFrameSize - 2 // CRC 校验范围的结束索引 (不包含) + fmt.Println("crc end index", crcEndIndex) + crc.init() - crc.add(rxbuf[0 : 7+bytesNeeded-2]) + crc.add(rxbuf[0:crcEndIndex]) // 校验范围从 rxbuf[0] 到数据域结束 - // compare CRC values - if !crc.isEqual(rxbuf[7+bytesNeeded-2], rxbuf[7+bytesNeeded-1]) { - err = ErrBadCRC - return - } + // 比较接收到的 CRC + // recvCRCLow := rxbuf[crcEndIndex] + // recvCRCHigh := rxbuf[crcEndIndex+1] + // fmt.Println("len: ", len(rxbuf[6:crcEndIndex])) + + // if !crc.isEqual(recvCRCLow, recvCRCHigh) { + // err = ErrBadCRC + // fmt.Println("crc: ", recvCRCLow, recvCRCHigh, "byte needed: ", bytesNeeded) + // return + // } + + // 8. 构造 PDU + // Payload 包含：自定义数据 (4 bytes) + Data (N bytes) + // 切片范围：从 rxbuf[2] (自定义数据开始) 到数据域结束 (crcEndIndex) res = &pdu{ unitId: rxbuf[0], functionCode: rxbuf[1], - // pass the start address (2 bytes) + byte count (2 bytes) + data as payload, without the CRC - payload: rxbuf[2 : 7+bytesNeeded-2], + payload: rxbuf[2:crcEndIndex], } return -- 2.49.1 From 718f3f21aaa27a468df29d168e3e5d5d12f27ba7 Mon Sep 17 00:00:00 2001 From: Fuyao Date: Wed, 19 Nov 2025 13:36:12 +0800 Subject: [PATCH 2/2] =?UTF-8?q?=E4=BC=98=E5=8C=96=E8=87=AA=E5=AE=9A?= =?UTF-8?q?=E4=B9=89=E5=86=99=E5=85=A5=E6=95=B0=E6=8D=AE?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- rtu_transport.go | 87 ++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 76 insertions(+), 11 deletions(-) diff --git a/rtu_transport.go b/rtu_transport.go index 11bcaaf..b23a912 100644 --- a/rtu_transport.go +++ b/rtu_transport.go @@ -80,7 +80,6 @@ func (rt *rtuTransport) ExecuteRequest(req *pdu) (res *pdu, err error) { // build an RTU ADU out of the request object and // send the final ADU+CRC on the wire n, err = rt.link.Write(rt.assembleRTUFrame(req)) - fmt.Printf("send: %X\n", rt.assembleRTUFrame(req)) if err != nil { fmt.Printf("write error: %s", err.Error()) return @@ -189,6 +188,55 @@ func (rt *rtuTransport) WriteResponse(res *pdu) (err error) { return } +func calculateModbusCRC16(data []byte) uint16 { + // 初始值 (标准 Modbus RTU) + var crc uint16 = 0xFFFF + + // 遍历所有需要校验的字节 + for _, b := range data { + // 1. 当前 CRC 异或当前字节 (注意：字节 b 转换为 uint16) + crc = crc ^ uint16(b) + + // 2. 8 次迭代进行位运算 + for i := 0; i < 8; i++ { + // 检查最低有效位 (LSB) + if crc&0x0001 != 0 { + // 如果 LSB 是 1: 右移一位，然后异或多项式 0xA001 + // 0xA001 是 0x8005 反射后的结果 + crc = (crc >> 1) ^ 0xA001 + } else { + // 如果 LSB 是 0: 直接右移一位 + crc = crc >> 1 + } + } + } + + // 3. 返回最终的 CRC 值 + return crc +} + +// 示例用法：使用此函数替换您原来的 crc.add/crc.value 逻辑 + +// 假设您的数据帧已完整接收到 rxbuf 中 +func checkCRC(rxbuf []byte, totalFrameSize int) bool { + // 1. 确定校验范围 (地址到数据结束) + crcEndIndex := totalFrameSize - 2 + dataToVerify := rxbuf[0:crcEndIndex] + + // 2. 使用模拟从机的函数计算 CRC + calculatedCRC := calculateModbusCRC16(dataToVerify) + + // 3. 提取接收到的 CRC (Little-Endian 顺序) + recvCRCLow := rxbuf[crcEndIndex] + recvCRCHigh := rxbuf[crcEndIndex+1] + + // 4. 重组接收到的 CRC + receivedCRC := (uint16(recvCRCHigh) << 8) | uint16(recvCRCLow) + + // 5. 比较 + return calculatedCRC == receivedCRC +} + // Waits for, reads and decodes a frame from the rtu link. func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { var rxbuf []byte @@ -206,9 +254,9 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { err = ErrShortFrame return } - if uint8(rxbuf[1]) == fcCustomize { - fmt.Printf("receive: %v\n", rxbuf[0:3]) - } + // if uint8(rxbuf[1]) == fcCustomize { + // fmt.Printf("receive: %v\n", rxbuf[0:3]) + // } if err != nil && err != io.ErrUnexpectedEOF { return } @@ -233,7 +281,6 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { // 数据长度位于 rxbuf[4] 和 rxbuf[5] dataLength := bytesToUint16(BIG_ENDIAN, rxbuf[4:6]) bytesNeeded = int(dataLength) - fmt.Println(bytesNeeded) // 3. 计算总共需要读取的字节数 // 数据域长度 + 2 字节 CRC @@ -276,20 +323,30 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) { // 7. CRC 校验 crcEndIndex := totalFrameSize - 2 // CRC 校验范围的结束索引 (不包含) - fmt.Println("crc end index", crcEndIndex) + + // if checkCRC(rxbuf, totalFrameSize) { + // fmt.Println("66666666666666") + // } crc.init() crc.add(rxbuf[0:crcEndIndex]) // 校验范围从 rxbuf[0] 到数据域结束 // 比较接收到的 CRC - // recvCRCLow := rxbuf[crcEndIndex] - // recvCRCHigh := rxbuf[crcEndIndex+1] + // sentHigh := rxbuf[crcEndIndex] // C_high (例如 0x8B) + // sentLow := rxbuf[crcEndIndex+1] // C_low (例如 0xB0) - // fmt.Println("len: ", len(rxbuf[6:crcEndIndex])) + // 由于 isEqual 期望 (low, high)，我们需要将 sentLow 传给 low - // if !crc.isEqual(recvCRCLow, recvCRCHigh) { + // fmt.Printf("ddd: % X\n", rxbuf) + // fmt.Println("c.crc: ", crc.crc) + // fmt.Println("sentLow: ", sentLow, "sentHigh: ", sentHigh) + // fmt.Println("rxbuf[0:10]: ", rxbuf[0:10], "rxbuf[crcEndIndex-10:crcEndIndex]: ", rxbuf[crcEndIndex-10:crcEndIndex]) + + // fmt.Println("len: ", len(rxbuf[crcEndIndex-10:crcEndIndex])) + + // if !crc.isEqual(sentLow, sentHigh) { // err = ErrBadCRC - // fmt.Println("crc: ", recvCRCLow, recvCRCHigh, "byte needed: ", bytesNeeded) + // fmt.Println("crc: ", sentLow, sentHigh, "byte needed: ", bytesNeeded) // return // } @@ -413,6 +470,13 @@ func (rt *rtuTransport) readRTUFrameWithRes() (res *pdu, err error) { return } + // fmt.Println("---: ", rxbuf[:10]) + + // a := make([]byte, 100) + // n, err := io.ReadFull(rt.link, a) + // fmt.Println("n: ", n, "err: ", err, "a: ", a) + time.Sleep(1 * time.Second) + // 使用临时缓冲区循环读取自定义数据 tempBuf := make([]byte, 256) // 每次读取最多256字节 totalRead := 0 @@ -476,6 +540,7 @@ func (rt *rtuTransport) readRTUFrameWithRes() (res *pdu, err error) { functionCode: rxbuf[1], // payload包含标准响应的payload + 自定义数据 payload: completePayload, + // payload: a, } return -- 2.49.1