First Node Project

Hello all,
I was curious to see if anyone has had experience using node-red with a BannerDXM 100. This is my first time using node-red and would like to potentially shift some projects over to it in the future. I have been using the node-red-contrib-modbus package. After playing with the nodes I for some reason can not read my holding registers correctly.

This is a link to the banner api documentation.

As of right now we use a simple visual basic program HMI to read registers over a tcp client.

Public Function Read_Remote_Registers(server As String, port As Int32, StartReg As Int16, RegCount As Int16, Slave_ID As Int16) As ArrayList
SyncLock SocketConnections
Connect(server, port)
Dim Read_Remote_Register_Array As New ArrayList
//Example use
//Dim Register_Array As ArrayList
//Register_Array = Read_Registers(201, 2, 0)
//TextBox1.Text = Register_Array(2)
//This will read 2 registers starting at register 201 from the processing board slave ID = 0 and build an array
//Next we return register 202 the second register from the array to a textbox

        //Begin connection and registry read
        //Server = Form_Connection_Settings.TextBox_IP_Address.Text
        //Port = Form_Connection_Settings.TextBox_Port.Text
            // Translate the passed message into ASCII and store it as a Byte array.
            //CMD0001 StartReg, RegCount, Slave ID (=0 for Processing Board, =200 for I/O Board), Modbus CMD, Timeout
            //RSP0001 StartReg, CSV Data 
            Dim data As [Byte]() = System.Text.Encoding.ASCII.GetBytes("CMD0003 " & StartReg & "," & RegCount & "," & Slave_ID & ",0,0")
           //Dim client As New TcpClient(Server, Port)
            client.SendTimeout = 1000
            client.ReceiveTimeout = 1000
            //Get a client stream for reading and writing.
            Dim stream As NetworkStream = client.GetStream()

           //Send the message to the connected TcpServer. 
            stream.Write(data, 0, data.Length)

            Dim bytes(client.ReceiveBufferSize) As Byte
            //Read can return anything from 0 to numBytesToRead. 
            //This method blocks until at least one byte is read.
            stream.Read(bytes, 0, CInt(client.ReceiveBufferSize))

            //Returns the data received from the host to the console.
            Dim returndata As String = Encoding.ASCII.GetString(bytes)

            //Convert to array
            Dim values As String = returndata
            Read_Remote_Register_Array.RemoveAt(Read_Remote_Register_Array.Count - 1)
            Read_Remote_Register_Array(0) = Mid(returndata, 1, 7)

            Read_Remote_Registers = Read_Remote_Register_Array

            //Close everything.
            Read_Remote_Registers = Read_Remote_Register_Array
            //Error Catch
        End Try
    End SyncLock
End Function

Im not experienced with nodejs so I have no idea how to convert that into javascript

JS isn't so hard. A few pointers:

  • Dim someVarName As <type> - JavaScript is typeless (mainly) you don't generally have to declare a variable as a particular type. Slight exception for Array's or Objects
  • Dim someVarName As <type> => var someVarName = 'stringvalue' 1 (or const or let)
  • Dim bytes(client.ReceiveBufferSize) As Byte => That would be referred to as a buffer in JS. 1
  • Try ... => try { .... } catch (err) { ... } 1, 2
  • Functions