3 replies to this topic

[caEstrada]

Hi there, Have you ever needed Modbus RTU using Netduino+ over a RS-485 network? Or do you need a Netduino with RS-485? Do it inexpensively with MAX483 connected directly to COM1 on the Netduino. Do you need a TCP to Serial Converter? You can do it with Netduino+ and the MAX483. Max483 works like a transceiver. The attached code allows to switch to transmit a Modbus message and turns on the receiver to catch the reply.

Attached Files

•  Netduino + MAX483 Uart To RS485.jpg   38.23KB   282 downloads
•  Program.cs   9.99KB   171 downloads

[HoosierInnovative]

Very interesting, so would you just use this to watch Modbus network traffic or can you communicate directly with a PLC?

[caEstrada]

Very interesting, so would you just use this to watch Modbus network traffic or can you communicate directly with a PLC?

If you know the protocol (Profibus, DH+, Optomux, etc.) you can write the code and have communication...

Regards,

[sayantan]

Hi there, Have you ever needed Modbus RTU using Netduino+ over a RS-485 network? Or do you need a Netduino with RS-485? Do it inexpensively with MAX483 connected directly to COM1 on the Netduino. Do you need a TCP to Serial Converter? You can do it with Netduino+ and the MAX483. Max483 works like a transceiver. The attached code allows to switch to transmit a Modbus message and turns on the receiver to catch the reply.

Hi caestrada,

i was trying out ur coding for my netduino plus 1 and rs485 communication, but while deploying the code its showindg

"Error 1 'System.IO.Ports.SerialPort' does not contain a definition for 'ReadByte' and no extension method 'ReadByte' accepting a first argument of type 'System.IO.Ports.SerialPort' could be found (are you missing a using directive or an assembly reference?) C:\Users\CSIO\Documents\Visual Studio 2010\Projects\ceNetduinoPlusModbusRTU42\ceNetduinoPlusModbusRTU42\Program.cs 277 40 ceNetduinoPlusModbusRTU42 "

this error, cn u pls help me to over come dis problem.

thank you.