skywatcher.protocol

Introduction


Please use the source code as a reference source

How to talk with Axis

The protocol of communication contains three basic elements.

The Target Axis: An char represented which axis the command is sent to.
value '1' means the following command is sent to AXIS1 (AZ/RA).
value '2' means the following command is sent to AXIS2 (ALT/DEC).
The Command: A char represented what action the target axis should react.
Data String: A byte string for the command, if necessary. It may contain some encoding, depends on the command itself.
How to send a request to the mount?

The command send with data string (length N) to the mount, would look like:

|Index |0| 1| 2| 3 ~ 3+N| 3+N+1| |:------|:|:-|:-|:-------|:-----| |Value 
|Leading Char, ':'| command, char| Target Axis, '1' or '2'| The data string body, if any| Ending Char, 13|

The Sample code

``` protected override void SendRequest(AXISID Axis, char Command, string cmdDataStr) { if (cmdDataStr == null) cmdDataStr = "";

        const int BufferSize = 20;
        StringBuilder CommandStr = new StringBuilder(BufferSize);
        CommandStr.Append(cStartChar_Out); // 0: Leading char
        CommandStr.Append(Command);        // 1: Length of command( Source, distination, command char, data )

        // Target Device
        CommandStr.Append(Axis == AXISID.AXIS1 ? '1' : '2');    // 2: Target Axis
        // Copy command data to buffer
        CommandStr.Append(cmdDataStr);

        CommandStr.Append(cEndChar);    // CR Character            

        mConnection.Write(CommandStr.ToString());
    }
```

How to read the response

| Index | 0 | 1 ~ N | N+1 | |:------|:---|:--------|:------| 
| Value | response or error message, '=' or '!'| response data body | Ending Char, 13|

The Sample Code

``` protected override string RecieveResponse() { 
// Receive Response // format "::e1\r=020883\r" long startticks = DateTime.Now.Ticks;

        StringBuilder mBuffer = new StringBuilder(15);
        bool StartReading = false, EndReading = false;

        int index = 0;
        long interval = 0;
        while (!EndReading)
        {
            index++;
            long curticks = DateTime.Now.Ticks;
            interval = curticks - startticks;

            if ((curticks - startticks) > 10000 * 1000)
            {
                //Trace.TraceError("Timeout {0} / {1}", mConnection.mBuffer, mBuffer);          
                throw new TimeoutException();
            }

            string r =mConnection.Read();

            for (int i = 0; i < r.Length; i++)
            {
                // this code order is important
                if (r[i] == cStartChar_In || r[i] == cErrChar)
                    StartReading = true;

                if (StartReading)
                    mBuffer.Append(r[i]);

                if (r[i] == cEndChar)
                {
                    if (StartReading)
                    {
                        EndReading = true;
                        break;
                    }
                }
            }

            Thread.Sleep(1);
        }

        //Trace.TraceInformation("Loop :" + index.ToString() + "Ticks :" + interval);
        return mBuffer.ToString();
    }
```
Command Set | Command Name| Command| Variable| Return| Description | 
|:------------|:--------|:---------|:-------|:-------------| 
| Initialize | F | | | Initial the target axis | 
| InquireMotorBoardVersion| e | | Encoded String| | Inquire Motor Board Version | 
| InquireGridPerRevolution| a | | Encoded String| Inquire Grid Ratio | 
| InquireTimerInterruptFreq| b | | Encoded String| Inquire Timer Interrupt Frequency | 
| InquireHighSpeedRatio| g | | Encoded String| Inquire High Speed Ratio | 
| InquirePECPeriod| s | | Encoded String| Inquire PEC Period | 
| AxisStop (Instant Stop)| L | | | Stop the target axis instantly | 
| AxisStop (Not Instant stop)| K | | | Stop the target axis normally | 
| SetAxisPosition| E | Encoded String| | Set the target axis position to the specify value | 
| GetAxisPosition| j | | Encoded String| Get the target axis position | 
| GetAxisStatus| f | | Encoded String| Get the target axis's status | 
| SetSwitch | O | '1' turn on , '0' turn off| | Turn On/Off of the trigger | 
| SetMotionMode| G | '0' high speed GOTO slewing, 
  		     '1' low speed slewing mode, 
		     '2' low speed GOTO mode, 
		     '3' High slewing mode| | Set the different motion mode | 
| SetGotoTargetIncrement| H | Encoded String| | Set the goto target increment | 
| SetBreakPointIncrement| M | Encoded String| | Set the break point increment | 
| SetBreakSteps| U | Encoded String| | Set the Break Steps| 
| SetStepPeriod| I | Encoded String| | Set the step counts| 
| StartMotion | J | | | Start motion based on previous settings |