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标题: 采用PLC作为服务器保存数值，然后用jamodmodbus客户端写代码从PC连接到PLC，读取PL... [打印本页]

作者: baikhgmv 时间: 2016-3-21 12:15
标题: 采用PLC作为服务器保存数值，然后用jamodmodbus客户端写代码从PC连接到PLC，读取PL...
采用PLC作为服务器保存数值，然后用jamodmodbus客户端写代码从PC连接到PLC，读取PLC寄存器值。值始终为零
我用PLC作为服务器和写代码读取寄存器值（DB10。data files）如图片贴在下面。我用jamodmodbus客户端写代码从PC连接到PLC寄存器（DB10。data files）。
结果是：我可以连接到PLC的成功，将请求发送到PLC的输出响应值，但我从寄存器（DB10。data files）PLC总是零（00）。我怎样才能解决这个问题，请告诉我使用代码从寄存器读取值（DB10。data files）和改变他们的小数？
这是我个人电脑上的代码：
package testmodbus;
import java.lang.*;
import java.net.InetAddress;
import java.net.SocketTimeoutException;
import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.ModbusSlaveException;
import net.wimpi.modbus.io.ModbusTCPTransaction;
import net.wimpi.modbus.msg.WriteCoilRequest;
import net.wimpi.modbus.msg.ReadInputRegistersRequest;
import net.wimpi.modbus.msg.ReadInputRegistersResponse;
import net.wimpi.modbus.net.TCPMasterConnection;
public class TestModbus {
public static void main(String[] args) throws ModbusSlaveException, SocketTimeoutException{
      // TODO code application logic here
      try {
         /* The important instances of the class */
         TCPMasterConnection con = null; // the connection
         ModbusTCPTransaction trans = null; // the transaction
         ReadInputRegistersRequest rreq = null; // the read request
         ReadInputRegistersResponse rres = null; // the read response
         WriteCoilRequest req = null; // the write request
         int ref = 40000; //the reference; offset where to start reading from

         int count =0;
         int repeat = 2;
         /* Variables for storing the parameters */
         InetAddress addr = null; // the slave's address
         int port = Modbus.DEFAULT_PORT; // DEFAULT_PORT = 502.
         // 1. Setup ?":>the parameters
         addr = InetAddress.getByName("192.168.0.1"); // ** The address of PLC
         // 2. Open the connection
         con = new TCPMasterConnection(addr);
         con.setPort(port);
         con.connect();
         System.out.println("--- Message: Line:36 success --- ");
         System.out.println("Connect to PLC sucessfull!!");
         // ~~~~~~~~~~~~~~~~~~~~ The faulty Read Request ~~~~~~~~~~~~~~~~~~~~
//          // 3r. Prepare the READ request
rreq = new ReadInputRegistersRequest(ref, count);
         System.out.println("The reqquest values =" + rreq.getHexMessage());
         System.out.println("--- Message: Line:42 success --- ");
////          // 4r. Prepare the READ transaction
         trans = new ModbusTCPTransaction(con);
         trans.setRequest(rreq);
/          System.out.println("--- Message: Line:46 success --- ");
////          // 5r. Execute the READ transaction
         int k = 0;
         do {
         trans.execute();

         rres =  (ReadInputRegistersResponse) trans.getResponse();
         System.out.println("The reqquest values =" + rreq.getHexMessage());
         System.out.println("getHexMessage of resspond = "+ rres.getHexMessage());

         k++;
         }while (k<repeat);
         // 6. Close the connection
         con.close();
      } catch (Exception e) {
         e.printStackTrace();
      }
}
}

这是我从控制台得到的输出代码：
run:
--- Message: Line:36 success ---
Connect to PLC sucessfull!!
The reqquest values =00 00 00 00 00 06 00 04 9c 40 00 00
--- Message: Line:42 success ---
--- Message: Line:46 success ---
The reqquest values =00 01 00 00 00 06 00 04 9c 40 00 00
getHexMessage of resspond = 00 01 00 00 00 03 00 04 00
The reqquest values =00 02 00 00 00 06 00 04 9c 40 00 00
getHexMessage of resspond = 00 02 00 00 00 03 00 04 00 // always get 00 values form PLC with whatever address I try to read from PLC.
BUILD SUCCESSFUL (total time: 0 seconds)

回答一：如果客户端/主请求数据来自于保持寄存器，则在请求消息和响应消息中出现功能代码03。
如果你的例子是十六进制查询或响应
的reqquest值= 00 00 00 00 00 06 00 04 40 00 00 9C
信息：路线：42成功---
信息：路线：46成功---
的reqquest值= 00 01 00 00 00 06 00 04 40 00 00 9C
对resspond = 00 01 00 00 00 03 00 04 00 gethexmessage
的reqquest值= 00 02 00 00 00 06 00 04 40 00 00 9C
然后在任何消息中我都没有看到03个函数代码。
您确定在保持寄存器中的数据吗？
你发送（fc03）设置保持寄存器？

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