6 replies to this topic

[Cinelli]

Hi, we are working with RS485 shields. Correct me if I'm wrong but it appears COM1 is routed through analog pins 0 & 1 TX/RX. This is just to do something we had running previously on other .Net MF platforms with no issues. We set up the COM port, added 5 seconds extra wait time to fill the COM buffer, and then read the whole buffer. The buffer only contains some of the bytes, so partial data received. We are using the Microsoft.SPOT.Hardware.SerialPort library (I assume Netduino uses this also). Can you link or paste in sample code for setting up the COM port (4.1 or 4.2)? We would like to assure we are doing this right. We did it in 2.5, then made the switch to the new 3.5+ COM port setup. The same shield (physically the same one, not just the same type) worked in another Arduino-format application, so it's unlikely to be the hardware. TIA.

[Chris Walker]

Hi Cinelli, Are you using analog pins 0/1 or digital pins 0/1? The serial ports are D0/D1 (COM1) and D2/D3 (COM2). Chris

[Cinelli]

Sorry, I did mean the Digital pins. Refernce this shield though we use others also: http://tinyurl.com/3hodmg2 Thanks Chris, love the Netduino project and Secret Labs hardware.

[Chris Walker]

Okay it looks like you're using the right pins. Can you post a small snippet of your old and new code? The new code should look pretty much like the .NET (desktop) way of doing things. Chris

[Luca Monaco]

Sorry, I did mean the Digital pins. Refernce this shield though we use others also:
http://tinyurl.com/3hodmg2

Thanks Chris, love the Netduino project and Secret Labs hardware.

Hi Cinelli,
I am very interested to this shield, but I never used it.
In shield documentation they said:
"The chip's DE (output enable) pin (3) is connected (via a resistor) to the Arduino's Digital Pin 2 - this is active high.
This DE pin is also connected to the chip's RE bar (receiver enable) pin (2) and therefore controlled by the Arduino's Digital pin 2 too - this is active low.
Arduino Digital Pin 2 = Rx/Tx 'Enable'; High to Transmit, Low to Receive"

So you have use also the Digital Pin 2.
Set it to true before trasmit data,
Set it to false after tasmitted data.

Let us know if it works.

[rht]

Hi, it looks like we are running into this or a similar problem with the http://linksprite.co...eld_for_Arduino shield. Can anybody provide more information or code? We've tested our code using an emulator and the rs485 device coms as well. The shield blips once TX but never receives a RX. Not sure yet how to debug this further. Any tips appreciated. 

Thanks!

GG

[pvanroos]

Hi all,

 

Did anyone ever figure this out?  I've got a RS-485 Shield from LinkSprite and I can't get it work.  Here are some details from my project:

 

1. Linksprite RS-485 Shield V2.1 - http://linksprite.co...2.1_for_Arduino

2. Using SerialPort for communication:  http://msdn.microsof...y/ee432679.aspx

3. Communicating over CAT6 twisted pair to a device at other end expecting 9600 baud, Even parity, 7 character bits, and one stop bit.

4. Twisted pair inserted into H2 485-A and 485-B ports.

5. Netduino Plus 2 (bought a month ago with no firmware updates)

6. Set to 5V using jumper.

7. Set to D0 and D1 using jumper.

8. Set to TX_CTRL using jumper.

9. Plugged into computer to deploy code.  Headers are not soldered but they fairly snug and not loose.

10: Code:

        static SerialPort serial;
        static OutputPort led;
        const int bufferMax = 10000;
        static byte[] buffer = new byte[bufferMax];
        static int bufferLength = 0;

        public static void Main()
        {         
            led = new OutputPort(Pins.ONBOARD_LED, false);
            serial = new SerialPort(SerialPorts.COM1, 9600, Parity.Even, 7, StopBits.One);
            serial.ReadTimeout = 1000;      
            serial.DataReceived += serial_DataReceived;
            serial.ErrorReceived += serial_ErrorReceived;
            serial.Open();

            while (true)
            {
                {
                    led.Write(true);
                   
                    Debug.Print("Request sent");
                    string hexrequest = "2F3F3030303330303030313039363030210D0A";
                
                    // Create request
                    byte[] seq = StringToByteArray(hexrequest);

                    if (serial.CanWrite)
                        serial.Write(seq, 0, seq.Length);    
                                           
                    led.Write(false);
                }

                string line = "> ";

                for (int i = 0; i < bufferLength; i++)
                {
                    line += buffer[i] + ",";
                }

                Debug.Print(line);
                if(serial.IsOpen) Debug.Print("Port is open.");
                Thread.Sleep(10000);
            }
        }
        static void serial_ErrorReceived(object sender, SerialErrorReceivedEventArgs e)
        {
            if (e.EventType == SerialError.TXFull)
            {
                Debug.Print("Error:  TXFull");
            }
            else if (e.EventType == SerialError.RXParity)
            {
                Debug.Print("Error:  RXParity");
            }
            else
            {
                Debug.Print("Error:  Some other error");
            }
        }

        static void serial_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {

            Debug.Print(dataRecLineNumber + ": Data received ******* - " + t );
       
            int bytesReceived = serial.Read(buffer, bufferLength, bufferMax - bufferLength);
            if (bytesReceived > 0)
            {
                bufferLength += bytesReceived;
                if (bufferLength >= bufferMax)
                    throw new ApplicationException("Buffer Overflow.  Send shorter lines or increase lineBufferMax.");
            }
        }