英文:
golang : network response from ioutil.ReadAll() is empty, connection reset by peer
问题
我正在尝试测试从设备模拟器中执行简单的TCP MODBUS读取单个寄存器的操作。运行代码时，显示的响应是0字节，并出现"connection reset by peer"的消息。有任何关于为什么它不起作用的想法吗？
更新，我的请求是不正确的，正确的工作MODBUS TCP轮询代码如下：
package mainimport ("fmt""net")// TCP MODBUS clientfunc main() {conn, err := net.Dial("tcp", "192.168.98.114:502")if err != nil {fmt.Println(err)}numRegs := 1// 发送MODBUS TCP请求（注意，格式与MODBUS串行不同）request := []byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x01, 0x03, 0x00, 0x01, 0x00, 0x01}n, err := conn.Write(request)if err != nil {fmt.Println(err)}expectedResponseLen := 5 + 2 * numRegsresponse := make([]byte, expectedResponseLen)n, err = conn.Read(response)conn.Close()if err != nil {fmt.Println(err)}for i := 0; i < n; i++ {fmt.Printf("%02x ", response[i])}fmt.Println("\n")}
希望对你有帮助！
英文:
I'm trying to test out performing a simple TCP MODBUS read of a single register from a device emulator. When running the code it is showing a response of 0 bytes and I get the message "connection reset by peer". Any ideas as to why it's not working?
UPDATE, my request was incorrect, the correct working MODBUS TCP poll code is:
package mainimport ("fmt""net")// TCP MODBUS clientfunc main() {conn, err := net.Dial("tcp", "192.168.98.114:502")if err != nil {fmt.Println(err)}numRegs := 1# make a MODBUS TCP request (be careful, the format is different to MODBUS serial)request := []byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x01, 0x03, 0x00, 0x01, 0x00, 0x01}n, err := conn.Write(request)if err != nil {fmt.Println(err)}expectedResponseLen := 5 + 2 * numRegsresponse := make([]byte, expectedResponseLen)n, err = conn.Read(response)conn.Close()if err != nil {fmt.Println(err)}for i := 0; i < n; i++ {fmt.Printf("%02x ", response[i])}fmt.Println("\n")}
答案1
得分: 0
最初我认为fmt.Fprintf可能会在发送请求数据时进行更改，但是这个示例似乎工作正常。
然而，我仍然建议使用较低级别的Write/Read而不是fmt.Fprintf/ioutil.ReadAll：
req := []byte { 0x01, 0x03, 0x00, 0x01, 0x00, 0x01, 0xd5, 0xca }n, err := conn.Write(req)if err != nil {fmt.Println("写入错误：", err)return}fmt.Printf("已写入 %d 字节的请求：%#v", n, req)rsp := make([]byte, 64)n, err = conn.Read(rsp)fmt.Printf("接收到 %d 字节的响应：%#v", n, rsp[:n])if err != nil {fmt.Println("读取错误：", err)}
英文:
Originally I thought that fmt.Fprintf may be changing the request data on the way out, but this example seems to work OK.
However, I would still recommend using the lower-level Write/Read instead of fmt.Fprintf/ioutil.ReadAll:
req := []byte { 0x01, 0x03, 0x00, 0x01, 0x00, 0x01, 0xd5, 0xca }n, err := conn.Write(req)if err != nil {fmt.Println("write error:", err)return}fmt.Printf("wrote %d bytes for request: %#v", n, req)rsp := make([]byte, 64)n, err = conn.Read(rsp)fmt.Printf("received %d bytes in response: %#v", n, rsp[:n])if err != nil {fmt.Println("read error:", err)}
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