int tpriRdcLts::open(int *devHndl, char *devName, int portNum, int blocking = -1, struct sockaddr_in *pServer = NULL)

This function is identical to that for the tpriRdcTcp class with the following exception:

Inputs:

int portNum      Desired port number on the terminal server, starting with 1.

int tpriRdcLts::close(int devHndl)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcLts::read(int devHndl, char *rxBuf, int rxCnt, int blocking = -1)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcLts::write(int devHndl, char *txBuf, int txCnt)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcLts:: resetConn(char *devName, int ltsPort, char *password = NULL)

Reset a port on a Lantronix terminal server.  This is useful if a connection to the terminal server died unexpectedly such that the server thinks the connection is still present and will not allow new connections until the original is reset.

Inputs:

char *devName      Remote device name.

int ltsPort      Desired port number on the terminal server, starting with 1.

char *password      The privileged password on the terminal server.  If no password is provided "system" is assumed.

Return value:

If a connection was made to the terminal server then a zero will be returned regardless of whether or not the reset was successful.  A return value of -1 indicates that a connection could not be established.

Following is an example class definition and source code for a Lantronix driver using the static function calls above to loop a message through a port on a terminal server back into itself.  It requires that a loopback cable be plugged into the specified port on the Lantronix terminal server.

<DemoLts.cpp>
//------------------------------------------------------------------------
//    File Name        : DemoLts.cpp
//
//    Author           : TelePro, Inc.
//
//    Date (Original)  : 6/15/01
//
//    Hdwr/Sys Config  : Pentium III PC or greater
//                       Windows 2000
//
//    Revision History :
//    Rev     Date       Who/Description
//    1.00    06/15/01   AJ Johnson
//                       Initial Version 
//------------------------------------------------------------------------
//    COPYRIGHT (C) 2001
//    TELEPRO, INC.
//    ALL RIGHTS RESERVED
//
//    THIS SOFTWARE AND ALL INFORMATION AND IDEAS CONTAINED WITHIN
//    ARE THE PROPERTY OF TELEPRO, INC. AND ARE CONFIDENTIAL.
//    NEITHER THIS SOFTWARE NOR ANY PART NOR ANY INFORMATION
//    CONTAINED IN IT MAY BE DISCLOSED OR FURNISHED TO OTHERS
//    WITHOUT THE PRIOR WRITTEN CONSENT OF TELEPRO, INC.
//------------------------------------------------------------------------
//    Function Name: DemoLts
//
//    Function Description and Notes:
//         This program demonstrates communications through a Lantronix
//         terminal server using a loopback test and the static class
//         tpriRdcLts functions to connect, read, write, and close.
//
//    Function type:
//       "C" language void function
//------------------------------------------------------------------------

// Standard header includes
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>

// System specific header includes
#include "tpriNtRt.h"
#include "tpriRdcLts.h"

void _cdecl main(int argc, char **argv, char **envp)
   {
   // Variable declarations
   int rstatus = 0;        // this function's return status
   int fstatus = 0;        // function call return status
   int forever = 1;        // Set => 0 when processing loop should exit
   char rxBuf[128];
   char rxCnt = 0;
   char *txBuf = "Test loopback message";
   int txCnt = strlen(txBuf);
   int devHndl = -1;
   char devName[256];
   int portNum;
   int connStat;
   // --------------------------------------------------------------
   // Initialize process management global
   // ------------
   fstatus = tpriProc::Create();
   if (fstatus < 0)
      {
      // unable to initialize process
      LogMsg("DemoLts", DBSS, "Error initializing process commons\n");
      forever = 0;
      }
   else
      {
      LogMsg("DemoLts", DBSS, "DemoLts V1.00\n");
      }
   // --------------------------------------------------------------
   // Set up local process environment using process initialization
   // file parameters
   // --------------------------------------------------------------
   if (forever)
      {
      fstatus = tpriProc::PrIni(argc, argv);
      if (fstatus < 0)
         {
         // unable to initialize process
         LogMsg("DemoLts", DBSS, "Error initializing process\n");
         forever = 0;
         }
      }
   // --------------------------------------------------------------
   // Application Code:
   //     The following code will be run once on initial process execution
   // --------------------------------------------------------------
#ifndef UNDER_RTSS
   WSADATA wsaData;
   int socketInit;
   if (forever)
      {
      // set up windows sockets
      socketInit = WSAStartup(0x0020, &wsaData);
      if (socketInit != 0)
         {
         // error initializing windows sockets
         LogMsg("DemoLts", DBERR, "Error %d starting Windows sockets\n",
            GetLastError());
         forever = 0;
         }
      }
#endif

   if (forever)
      {
      if (argc <= 1)
         {
         LogMsg("DemoLts", DBFERR, 
            "Ini file not specified on command line\n");
         forever = 0;
         }
      else
         {
         // get the LTS IP address
         tpriIniFile::getKeyValue("LtsLoopback", "IPAddress", "localhost", 
            devName, sizeof(devName), argv[1]);

         // get the LTS port number
         tpriIniFile::getKeyValue("LtsLoopback", "LtsPort", "1", 
            rxBuf, sizeof(rxBuf), argv[1]);
         portNum = atol(rxBuf);
         }
      }

   // --------------------------------------------------------------
   // Try to connect
   // -------------------------------------------------------------
   while ((forever) && 
          ((connStat = tpriRdcLts::open(&devHndl, devName, 
                                        portNum, 0)) < 0))
      {
      // -----------------------------------------------------------
      // Call PrWait to stall until the next timer interval
      // -----------------------------------------------------------
      fstatus = tpriProc::PrWait();

      // --------------------------------------------------------
      // Decide whether or not to continue
      // -------------------------------------------------------
      forever &= (tpriProc::getState() > 0);
      }

   if (connStat == 0)
      {
      LogMsg("DemoLts", DBSS, "Connected to terminal server %s port %d\n",
         devName, portNum);

      // write a message out to the terminal server
      if (tpriRdcLts::write(devHndl, txBuf, txCnt) != txCnt)
         {
         LogMsg("DemoLts", DBERR, 
            "Error writing data to terminal server\n");
         }
      else 
         {
         LogMsg("DemoLts", DBERR, 
            "Wrote loopback message <%s> to terminal server\n", txBuf);

         while (forever)
            {
            // read a bit of data
            fstatus = tpriRdcLts::read(devHndl, &rxBuf[rxCnt], 
                         sizeof(rxBuf) - rxCnt, 0);
            if (fstatus > 0)
               {
               // print out what we just received
               DumpHex(DEBUG, (unsigned char *)&rxBuf[rxCnt], 0, fstatus,
                  "Received data");

               // check if this new data completes the message
               rxCnt += fstatus;

               if (memcmp(rxBuf, txBuf, txCnt) == 0)
                  {
                  // bingo! - we got back what we sent
                  rxBuf[txCnt] = 0x00;
                  LogMsg("DemoLts", DBSS, 
                     "Received full loopback message <%s>\n", rxBuf);

                  // fall out of the loops
                  forever = 0;
                  }
               }
               
            // -----------------------------------------------------
            // Call PrWait to stall until the next timer interval
            // -----------------------------------------------------
            fstatus = tpriProc::PrWait();
            
            // ---------------------------------------------------
            // Decide whether or not to continue
            // ---------------------------------------------------
            forever &= (tpriProc::getState() > 0);
            }
         }
         
      // close the connection
      tpriRdcLts::close(devHndl);
      }
   // ----------------------------------------------------------
   // At this point the Application has decided that it no longer wants
   // to be run, so clean up and exit.
   // ------------------------------------------------------------
   LogMsg("DemoLts", DBSS, "Process exiting\n");
   tpriGsmDDCom::Destroy();
   tpriProc::Destroy();

   ExitProcess(rstatus);
   }

<LtsLoopback.ini>

#
#   Example Lantronix terminal server loopback program config file
#
[LtsLoopback]
IPAddress=192.55.195.222
LtsPort=1

The I/O driver library includes the tpriRdcCbx class for communications through a Lantronix CoBox terminal server to a remote device.  This class provides functions to open a connection to a specified port on the desired CoBox terminal server, to read and write data to and from the device attached to the terminal server, and to close the connection when finished.  Blocking and non-blocking modes are both supported individually for connections and reads.  The library is composed of several static class functions that can be explicitly called without having to manage the underlying class itself.

int tpriRdcCbx::open(int *devHndl, char *devName, int portNum, int blocking = -1, struct sockaddr_in *pServer = NULL)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcCbx::close(int devHndl)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcCbx::read(int devHndl, char *rxBuf, int rxCnt, int blocking = -1)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcCbx::write(int devHndl, char *txBuf, int txCnt)

This function is identical to that for the tpriRdcTcp class.

int tpriRdcCbx:: resetConn(char *devName, char *password = NULL)

Reset a port on a CoBox terminal server.  This is useful if a connection to the terminal server died unexpectedly such that the server thinks the connection is still present and will not allow new connections until the original is reset.

Inputs:

char *devName      Remote device name.

char *password      The privileged password on the terminal server.  If no password is provided "system" is assumed.

Return value:

If a connection was made to the terminal server then a zero will be returned regardless of whether or not the reset was successful.  A return value of -1 indicates that a connection could not be established.

In addition to the static library functions described above, the tpriRdc-derived classes can be used to as a framework to manage all of the low-level I/O, timing, and error recovery associated with a connection to a remote device.  In effect, the tpriRdc classes act as a fully customizable state machine to communicate with a remote device through a variety of interfaces without having to worry about the specifics of the intermediate hardware or basic communications protocols.  Currently, the following interfaces are supported:

• Direct serial RS-232

• Direct TCP/IP

• TCP/IP to serial via Lantronix 4-, 8-, and 16-port terminal servers

• TCP/IP to serial via Lantronix CoBox single-port terminal servers

The interface-specific tpriRdc classes are:

• tpriRdcSer           Direct serial RS-232

• tpriRdcTcp           Direct TCP/IP

• tpriRdcLts            Lantronix multi-port terminal server

• tpriRdcCbx           Lantronix CoBox terminal server

The custom device driver should be derived from one of these classes in order to build upon and use the functionality encapsulated within these classes.

Following is flow path for the state machine:

switch (current state)

      case UNINIT

• call virtual function initDrv()

case IDLE

• if first pass → goto state CONNECT

• else if reopen

  • set/test delay timer for reopen

• else return non-zero from state driver to indicate we’re finished

case CONNECT

• call virtual function setupComm(0) to open connection

• if success → goto state WAITMSG

• else if error →

  • call virtual function setupComm(1) to clean up

case WAITMSG

• call virtual function waitMsg() to check if it’s time to send a message

• if it’s time → goto state BUILDMSG

• else if it’s not yet time → continue waiting

case BUILDMSG

• call virtual function buildMsg() to assemble the outbound message

• if return = 0 → goto state XMITMSG

• else if error → return to state WAITMSG

case XMITMSG

• call virtual function xmitMsg() to send message

• if return = 0 → goto state WAITRSP

• else if error →

  • call virtual function setupComm(1) to clean up

  • return to state IDLE

case WAITRSP

• call waitRsp() to read data from interface

• call virtual function testRsp() to test if a full msg has been recv’d.

• if full msg recv’d → goto state PROCRSP to process valid message

• else if timeout → goto state PROCRSP to process empty message

• else if error →

  • call virtual function setupComm(1) to clean up

  • return to state IDLE

case PROCRSP

• call virtual function procRsp()

• if return is 0 → goto state WAITMSG

• else if error → goto state IDLE

The state machine for the remote device connection can be executed by calling the following function defined in the tpriRdc base class:

int tpriRdc:: stateDrv(int oneshot = 0)

Close a connection associated with a device handle.

Inputs:

int oneshot      If non-zero, the state machine will execute only once and return.  If zero, the state machine will repeatedly execute until the current state does not change from pass to pass. 

Return value:

Zero if no error and state machine can be called again to continue processing or non-zero if an error has occurred or the state machine has finished.

The state machine for the remote device connection can be executed by calling the following function defined in the tpriRdc base class:

The following variables are internal data members of the tpriRdc class and the custom driver class should set their values as desired:

The following variables are internal data members of the tpriRdcTcp class the custom driver class should set their values as desired:

The following variables are internal data members of the tpriRdc class that the custom device class will require for normal processing:

The custom device driver class then overrides a set of virtual functions that will be called by the base classes at the appropriate times.  These virtual functions are:

• Virtual int initDrv()
  The framework calls this function to process one-time initialization of internal parameters including device name, timeout values, max retry counts, etc.  Return zero to indicate success and nonzero to indicate that an error has occurred.
  

•  Virtual int setupComm(int oper)
  The framework calls this function to connect (oper <> 0) or disconnect (oper = 0) from the remote device.  Return zero to indicate success and nonzero to indicate that an error has occurred.  This function does not need to be overridden under normal circumstances.
  

•  Virtual int waitMsg()
  The framework calls this function to allow the derived class to decide when it is time to send a message to the remote device.  Return zero to indicate a message should now be sent and nonzero to continue waiting.
  

•  Virtual int buildMsg()
  The framework calls this function to assemble the next outbound message immediately after the user has returned zero from a call to waitMsg().  The custom driver should copy the outbound message into the class data member txBuf[] character buffer and store the number of characters in the class data member txCnt.
  

•  Virtual int xmitMsg()|
  The framework calls this function to transmit data to the remote device.  Return 0 to indicate success or nonzero indicate an error.  This function does not need to be overridden under normal circumstances.
  

•  Virtual int waitRsp()
  The framework calls this function to read data from the remote device.  It must also call testRsp() to check if a full message has been received.  Return 0 to indicate reception of a complete message or timeout or -1 to continue reading data.  This function does not need to be overridden under normal circumstances.
  

•  Virtual int testRsp()
  The framework calls this function to decide whether or not a response has been received from the remote device.  Upon entry into this function all data received from the remote device since transmission of the most recent message is stored in the class data member rxBuf[] character buffer and the number of received bytes stored in rxCnt.  Any bytes at the beginning of the rxBuf[] buffer that are not part of a valid response may be removed using the class member function tossRsp(int nToss).  If a valid message is found, copy it from the beginning of the rxBuf[] buffer to the response buffer using the class member function ripRsp(nRsp).  Return zero to indicate that the response is complete, less than zero to indicate that the response is incomplete, and greater than zero to indicate that an error has occurred.
  

•  Virtual int procRsp()
  The framework calls this function to process a complete response from the remote device.  Return zero to reset and wait until the next message should be sent, and nonzero to reset the connection.

The following functions are internal data methods of the tpriRdc class for use within the custom user driver:

int getState()

Return the current state.

Return value:

The current state is returned as specified in the following table:

UNINIT            0

IDLE            1

CONNECT           2

WAITMSG           3

BUILDMSG          4

XMITMSG           5

WAITRSP           6

PROCRSP           7

void setRxBufSize(int size)

Resize of the internal receive buffer.  Any data existing in the existing buffer will be transferred to the new buffer provided that it does not exceed the new size.  The default size of the receive buffer is 1024 bytes.

Inputs:

int size      New size of receive buffer.

void setTxBufSize(int size)

Resize of the internal transmit buffer.  Any data existing in the existing buffer will be transferred to the new buffer provided that it does not exceed the new size.  The default size of the transmit buffer is 1024 bytes.

Inputs:

int size      New size of transmit buffer.

void ripRsp(int nRsp)

Pops the first nRsp bytes from the receive buffer rxBuf[], dynamically allocates the response buffer *rspBuf, and stores the response there for later processing.  This function should be called from within the testRsp() virtual function once a full response starting at the beginning of the rxBuf buffer has been detected.  Each call to ripRsp(..) destroys the response buffer created by the previous call and shifts the receive buffer so that the remaining data is stored at the beginning of the buffer.

Inputs:

int nRsp      Number of bytes in the detected response that should be copied out of the receive buffer rxBuf[].

      void tossRsp(int nRsp)

Pops the first nRsp bytes from the receive buffer rxBuf[] and throws them away.  The receive buffer is then shifted so that the remaining data is stored at the beginning of the buffer.  This function should be called from within the testRsp() virtual function to throw away bytes at the beginning of the receive buffer that are not part of a valid response.

Inputs:

int nRsp   Number of bytes in the detected response that should be copied out of the receive buffer rxBuf[].

The Tsentry source distribution area contains an example class definition and source code for a tpriRdc-derived class used to loop a message through a port on a Lantronix multi-port terminal server back into itself.  It requires that a loopback cable be plugged into the specified port on the Lantronix terminal server.