C # Modbus Data read using NMODBUS4 Library

Modbus Communication Protocol

Method name	Role	Required Parameters	return value	corresponding function code
Readcoils	Read the status of Do	Slave address (8-bit) BYTE slaveaddress Start address (16-bit) UShort Startaddress Number of reads (16-bit) UShort Numberofpoints	Bool[]	01
Readinputs	Read the state of Di	Slave address (8-bit) BYTE slaveaddress Start address (16-bit) UShort Startaddress Number of reads (16-bit) UShort Numberofpoints	Bool[]	02
Readholdingregisters	Read the value of AO	Slave address (8-bit) BYTE slaveaddress Start address (16-bit) UShort Startaddress Number of reads (16-bit) UShort Numberofpoints	Ushort[]	03
Readinputregisters	Read the value of AI	Slave address (8-bit) BYTE slaveaddress Start address (16-bit) UShort Startaddress Number of reads (16-bit) UShort Numberofpoints	Ushort[]	04
Writesinglecoil	Write value to do	Slave address (8-bit) BYTE slaveaddress Coil Address (16-bit) UShort Coiladdress Write Value (Boolean) BOOL Value	No return value	05
Writesingleregister	Write value to AO	Slave address (8-bit) BYTE slaveaddress Register address (16-bit) UShort Registeraddress Write value (16-bit) UShort Value	No return value	06
Writemultiplecoils	Write multi-coil registers	Slave address (8-bit) BYTE slaveaddress Start address (16-bit) UShort Startaddress Write value (Boolean array) Bool[] Data	No return value	15
Writemultipleregisters	Write multiple hold Registers	Slave address (8-bit) BYTE slaveaddress Start address (16-bit) UShort Startaddress, Register value (16-bit integer array) Ushort[] Data	No return value	16
Readwritemultipleregisters	Read and write multiple hold registers	Slave address (8-bit) BYTE slaveaddress Read start address (16-bit) UShort Startreadaddress Number of reads (16-bit) UShort Numberofpointstoread, Write start address (16-bit) UShort Startwriteaddress, Write value (16-bit integer array) Ushort[] WriteData	Ushort[]	23

Modbus Slave

This is the installation package Modbusslavesetup64bit registration code:54555451475662

Modbus Communication Protocol Net Library

This is a lot of open source libraries, my side of the library is GitHub's open Source implementation class Library: Nmodbus4,github address: HTTPS://GITHUB.COM/NMODBUS4/NMODBUS4

I use Modbus slave to simulate a slave machine

Setting up data

NMODBUS4 Read Slave code example

1IPAddress address =NewIPAddress (New byte[] {127,0,0,1 });2             using(TcpClient client =NewTcpClient (address. ToString (),502))3             {4Client. Sendtimeout =1;5                 //Client.op6Modbusipmaster master =modbusipmaster.createip (client);7                 //Master.op8                 //read five input values9                 ushortStartaddress =0;Ten                 ushortNuminputs =Ten; One                 BOOL[] inputs = Master. Readcoils (1, startaddress, numinputs); A  -                  for(inti =0; i < numinputs; i++) -                 { theConsole.WriteLine ($"Input {(startaddress + i)}={(inputs[i]? 1:0)}"); -                 } -  -}

Here is worth noting is the host read method the first parameter is SlaveID if not added startaddress and numinputs Nmodbus will default SlaveID is 01 straight exception (d (╯﹏╰) B painful experience ~ ~)

The above data is the do state just set

In the demo of a read AI value

The code is not bad how much is the method readinputregisters different. Here is the sample code

1IPAddress address =NewIPAddress (New byte[] {127,0,0,1 });2             using(TcpClient client =NewTcpClient (address. ToString (),502))3             {4Client. Sendtimeout =1;5                 //Client.op6Modbusipmaster master =modbusipmaster.createip (client);7                 //Master.op8                 //read five input values9                 ushortStartaddress =0;Ten                 ushortNuminputs =Ten; One                 ushort[] inputs = Master. Readinputregisters (2, startaddress, numinputs); A  -                  for(inti =0; i < numinputs; i++) -                 { theConsole.WriteLine ($"Register {(startaddress + i)}={(Inputs[i])}"); -                 } -  -}

C # Modbus Data read using NMODBUS4 Library