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自定义实时数据读取&读标定信息

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This commit is contained in:
Fuyao
2025-11-17 11:01:51 +08:00
parent 1c4d54df71
commit 72429c08a3
2 changed files with 196 additions and 23 deletions
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81
client.go
View File

@@ -801,17 +801,27 @@ func (mc *ModbusClient) WriteRegisterWithRes(addr uint16, value uint16) (bytes [
// validate the response code
switch {
case res.functionCode == req.functionCode:
// expect 4 bytes (2 byte of address + 2 bytes of value)
if len(res.payload) != 4 ||
// bytes 1-2 should be the register address
bytesToUint16(BIG_ENDIAN, res.payload[0:2]) != addr ||
// expect at least 4 bytes (2 byte of address + 2 bytes of value)
// 后面可能还有自定义数据
if len(res.payload) < 4 {
err = ErrProtocolError
return
}
// bytes 1-2 should be the register address
if bytesToUint16(BIG_ENDIAN, res.payload[0:2]) != addr ||
// bytes 3-4 should be the value
bytesToUint16(mc.endianness, res.payload[2:4]) != value {
err = ErrProtocolError
return
}
bytes = req.payload[1:]
// 返回自定义数据（第4字节之后的数据）
if len(res.payload) > 4 {
bytes = res.payload[4:]
} else {
bytes = []byte{} // 没有自定义数据，返回空切片
}
case res.functionCode == (req.functionCode | 0x80):
if len(res.payload) != 1 {
@@ -1261,22 +1271,55 @@ func (mc *ModbusClient) readRegistersWithFunctionCode(addr uint16, quantity uint
switch {
case res.functionCode == req.functionCode:
// make sure the payload length is what we expect
// (1 byte of length + 2 bytes per register)
// if len(res.payload) != 1+2*int(quantity) {
// err = ErrProtocolError
// return
// }
// For custom function code 0x41, the payload format is:
// [起始地址(2字节)] [字节数(2字节)] [数据...]
if functionCode == fcCustomize {
// validate minimum payload length (start address 2 bytes + byte count 2 bytes)
if len(res.payload) < 4 {
err = ErrProtocolError
mc.logger.Errorf("payload too short for custom function code: %d bytes", len(res.payload))
return
}
// validate the byte count field
// (2 bytes per register * number of registers)
// if uint(res.payload[0]) != 2*uint(quantity) {
// err = ErrProtocolError
// return
// }
// extract byte count from payload (bytes 2-3, big endian)
byteCount := bytesToUint16(BIG_ENDIAN, res.payload[2:4])
// remove the byte count field from the returned slice
bytes = res.payload[1:]
// validate payload length matches expected data length
expectedLength := 4 + int(byteCount) // start address (2) + byte count (2) + data
if len(res.payload) != expectedLength {
err = ErrProtocolError
mc.logger.Errorf("payload length mismatch: expected %d, got %d", expectedLength, len(res.payload))
return
}
// validate byte count matches requested quantity
if byteCount != 2*quantity {
err = ErrProtocolError
mc.logger.Errorf("byte count mismatch: expected %d, got %d", 2*quantity, byteCount)
return
}
// extract only the data part (skip start address and byte count)
bytes = res.payload[4:]
} else {
// standard modbus protocol handling
// make sure the payload length is what we expect
// (1 byte of length + 2 bytes per register)
// if len(res.payload) != 1+2*int(quantity) {
// err = ErrProtocolError
// return
// }
// validate the byte count field
// (2 bytes per register * number of registers)
// if uint(res.payload[0]) != 2*uint(quantity) {
// err = ErrProtocolError
// return
// }
// remove the byte count field from the returned slice
bytes = res.payload[1:]
}
case res.functionCode == (req.functionCode | 0x80):
if len(res.payload) != 1 {

138
rtu_transport.go
View File

@@ -4,6 +4,7 @@ import (
"fmt"
"io"
"log"
"os"
"time"
)
@@ -192,6 +193,7 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) {
var byteCount int
var bytesNeeded int
var crc crc
var dataLength uint16
rxbuf = make([]byte, maxRTUFrameLength)
@@ -206,6 +208,73 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) {
return
}
// 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
}
// extract data length from bytes 5-6 (byte count field, big endian)
dataLength = bytesToUint16(BIG_ENDIAN, rxbuf[5:7])
bytesNeeded = int(dataLength)
// we need to read 2 additional bytes of CRC after the payload
bytesNeeded += 2
// calculate total frame size: 3 (header) + 4 (start addr + byte count) + data + 2 (CRC)
totalFrameSize := 7 + bytesNeeded
// for custom function code, we may need a larger buffer than maxRTUFrameLength
// allocate buffer dynamically if needed
if totalFrameSize > maxRTUFrameLength {
// save already read data
header := make([]byte, 7)
copy(header, rxbuf[0:7])
// resize buffer to accommodate larger frame
rxbuf = make([]byte, totalFrameSize)
// copy back the header
copy(rxbuf[0:7], header)
}
// read the data and CRC
byteCount, err = io.ReadFull(rt.link, rxbuf[7:7+bytesNeeded])
if err != nil && err != io.ErrUnexpectedEOF {
return
}
if byteCount != bytesNeeded {
rt.logger.Warningf("expected %v bytes, received %v", bytesNeeded, byteCount)
err = ErrShortFrame
return
}
// compute the CRC on the entire frame, excluding the CRC
crc.init()
crc.add(rxbuf[0 : 7+bytesNeeded-2])
// compare CRC values
if !crc.isEqual(rxbuf[7+bytesNeeded-2], rxbuf[7+bytesNeeded-1]) {
err = ErrBadCRC
return
}
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],
}
return
}
// standard modbus protocol handling
// figure out how many further bytes to read
bytesNeeded, err = expectedResponseLenth(uint8(rxbuf[1]), uint8(rxbuf[2]))
if err != nil {
@@ -305,16 +374,77 @@ func (rt *rtuTransport) readRTUFrameWithRes() (res *pdu, err error) {
return
}
_, err = io.ReadFull(rt.link, rxbuf[3+bytesNeeded:])
if err != nil && err != io.ErrUnexpectedEOF {
// 标准modbus响应已读取完成，现在读取自定义数据
// 设置5秒超时来读取自定义数据
customDataTimeout := 5 * time.Second
err = rt.link.SetDeadline(time.Now().Add(customDataTimeout))
if err != nil {
return
}
// 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
startPos := 3 + bytesNeeded
for {
// 检查缓冲区是否还有空间
if startPos+totalRead+len(tempBuf) > len(rxbuf) {
// 如果缓冲区不够，扩展它
newBuf := make([]byte, len(rxbuf)*2)
copy(newBuf, rxbuf)
rxbuf = newBuf
}
// 尝试读取数据
n, readErr := rt.link.Read(tempBuf)
if n > 0 {
// 将读取的数据复制到rxbuf
copy(rxbuf[startPos+totalRead:startPos+totalRead+n], tempBuf[:n])
totalRead += n
}
// 如果遇到超时错误，说明没有更多数据了
if readErr != nil {
if os.IsTimeout(readErr) {
// 超时是正常的，说明自定义数据读取完成
break
}
// 其他错误需要检查是否是EOF（数据读取完成）
if readErr == io.EOF {
break
}
// 对于其他错误，如果已经读取了一些数据，继续处理
if totalRead == 0 {
err = readErr
return
}
break
}
// 如果读取的字节数少于请求的，说明没有更多数据了
if n < len(tempBuf) {
break
}
}
// 返回标准响应的payload（地址+值，4字节）+ 自定义数据
// 标准响应的payload在 rxbuf[2:3+bytesNeeded-2] 位置
standardPayloadStart := 2
standardPayloadEnd := 3 + bytesNeeded - 2
// 构建完整的payload：标准响应payload + 自定义数据
completePayload := make([]byte, 0, standardPayloadEnd-standardPayloadStart+totalRead)
completePayload = append(completePayload, rxbuf[standardPayloadStart:standardPayloadEnd]...)
if totalRead > 0 {
completePayload = append(completePayload, rxbuf[startPos:startPos+totalRead]...)
}
res = &pdu{
unitId: rxbuf[0],
functionCode: rxbuf[1],
// pass the byte count + trailing data as payload, withtout the CRC
payload: rxbuf[3+bytesNeeded:],
// payload包含标准响应的payload + 自定义数据
payload: completePayload,
}
return