写多个保持寄存器 [英] Write multiple holding register

问题描述

我想通过下面的代码写一个保持寄存器（16位）。但是我没有成功。 '超时'例外发生。请告诉我我错在哪里。

代码如下。

I want to write a holding register(16 bit) by below code.but i have not got success. 'Time out' exception occures. Please suggest me where i am wrong.
Code is given below.

byte address = Convert.ToByte("127");
                ushort start = Convert.ToUInt16("15");
                short[] value = new short[1];
                value[0] = Convert.ToInt16("1");

                try
                {
                    while (!mb.SendFc16(address, start, (ushort)1, value)) ;
                }
                catch (Exception err)
                {
                    lblConfigurationBlockStatus.Text= err.Message;
                }
                lblConfigurationBlockStatus.Text=(mb.modbusStatus);

public bool SendFc16(byte address, ushort start, ushort registers, short[] values)
       {
           //Ensure port is open:
           if (sp.IsOpen)
           {
               //Clear in/out buffers:
               sp.DiscardOutBuffer();
               sp.DiscardInBuffer();
               //Message is 1 addr + 1 fcn + 2 start + 2 reg + 1 count + 2 * reg vals + 2 CRC
               byte[] message = new byte[9 + 2 * registers];
               //Function 16 response is fixed at 8 bytes
               byte[] response = new byte[8];

               //Add bytecount to message:
               message[6] = (byte)(registers * 2);
               //Put write values into message prior to sending:
               for (int i = 0; i < registers; i++)
               {
                   message[7 + 2 * i] = (byte)(values[i] >> 8);
                   message[8 + 2 * i] = (byte)(values[i]);
               }
               //Build outgoing message:
               BuildMessage(address, (byte)16, start, registers, ref message);

               //Send Modbus message to Serial Port:
               try
               {
                   sp.Write(message, 0, message.Length);
                   GetResponse(ref response);
               }
               catch (Exception err)
               {
                   modbusStatus = "Error in write event: " + err.Message;
                   return false;
               }
               //Evaluate message:
               if (CheckResponse(response))
               {
                   modbusStatus = "Write successful";
                   return true;
               }
               else
               {
                   modbusStatus = "CRC error";
                   return false;
               }
           }
           else
           {
               modbusStatus = "Serial port not open";
               return false;
           }
       }

推荐答案

基本上，这意味着你的SendFc16方法不断返回false。

可能发生这种情况的最简单原因是串口未打开。它可能不是 - 它可能是您报告的任何其他错误 - 但这就是我开始的地方。使用调试器，并按照代码查找返回false的原因。


而不是只是连续重试，将数字限制为合理数量：或者3：5或10：

Basically, it means that your SendFc16 method is continually returning false.
And the simplest reason why that might happen is that the serial port is not open. It may not be that - it could be any of the other errors you report - but that's where I'd start. Use the debugger, and follow the code through to find out why it is returning false.

And instead of just continual retries, limit the number to a "sensible" amount: 3, 5, or 10 perhaps:

try
    {
    int retries = 3;
    while (!mb.SendFc16(address, start, (ushort)1, value)) 
        {
        if (--retries == 0) break;
        }
    }

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