Agilent 54622D O-scope

// agilentscope.c - GNU g++ egcs-2.91.66, V. Bancroft  1999
//Fixed to run on ubuntu linux 2018
//src from documentation. --fixed errors
#include <stdlib.h>
#include <string.h>
#include <stdio.h>     // ISO C Standard: 4.9 INPUT/OUTPUT
#include <time.h>      // ISO C Standard: 4.12 DATE and TIME
#include <termios.h>   // POSIX Standard: 7.1-2 General Terminal Intf.
#include <unistd.h>    // POSIX Standard: 2.10 Symbolic Constants
#include <fcntl.h>     // POSIX Standard: 6.5 File Control Operations
#include <sys/types.h> // POSIX Standard: 2.6 Primitive System Data Types
#include <sys/stat.h>  // POSIX Standard: 5.6 File Characteristics

#define DWORD                size_t
// a file handle is an integer descriptor,
#define HANDLE               int
// open failure results in negative one,
#define INVALID_HANDLE_VALUE -1
// default device string
#define DEVICE               "/dev/ttyUSB0"
// define values for iSerOK
#define TRUE                 1
#define FALSE                0
HANDLE   hSerPort;     // Global variables
int      iSerOK;
void SerMessage(char* msg1, char* msg2)
// Displays a message to the user.
// msg1 = main message
// msg2 = message caption
// Change this to your preferred way of displaying msgs.
{
  printf( "%s ( %s )\n", msg1, msg2);
}
void SerCrash(char* msg1, char* msg2)
// Like SerMessage, but ends the program.
{
  SerMessage(msg1,msg2);
  iSerOK = 0;
}
int SerOK()
// Returns nonzero if most recent operation succeeded,
// or 0 if there was an error
{
  return iSerOK;
}
void SerOpen(char* portname, char* handshake)
// Opens the serial port.
// portname = "COM1", "COM2", etc.
// handshake = "RTS" or "DTR"
{
  //
  // Open the port using a handle
  //
  hSerPort = open( portname, O_RDWR );
  if (hSerPort == INVALID_HANDLE_VALUE) {
    SerCrash("Can't open comm port",portname);
    iSerOK = FALSE;
  }

  struct termios term;
  if ( tcgetattr( hSerPort, &term ) ) {
    SerMessage( "Can't get device settings.", "tcgetattr");
    iSerOK = FALSE;
  }
  // Now choose the handshaking mode...
  if ((handshake[0] == 'r') || (handshake[0] == 'R'))
  {
    term.c_cflag =  CRTSCTS;    // RTS/CTS flow control of output
  }
  else
  {
    term.c_cflag &=  ~( CRTSCTS ); // disable CTS flow control of output
  }
  //
  // Set baud rate and other attributes
  //
  term.c_cflag |=   CS8;      // eight bit character set
  term.c_cflag |=  CREAD;    // enable receiver
  term.c_cflag |=  HUPCL;    // lower modem lines on last close
  term.c_cflag |=  CLOCAL;   // ignore modem status lines
  term.c_iflag = 0;          // turn off input processing
  // term.c_iflag = IGNPAR;     // ignore parity errors
  term.c_lflag = 0;          // turn off local processing
  term.c_oflag = 0;          // turn off output processing

cfsetispeed( &term, B9600 );
  cfsetospeed( &term, B9600 );
  if (tcsetattr( hSerPort, TCSANOW, &term )) {
    SerCrash("Bad parameters for port",portname);
    iSerOK = FALSE;
  }
  if (!iSerOK) SerCrash("Bad parameters for port",portname);
  //
  // Disable Windows' timeouts; we keep track of our own
  //
  // COMMTIMEOUTS t = {MAXDWORD,0,0,0,0};
  // SetCommTimeouts(hSerPort,&t);
}
void SerClose()
// Closes the serial port.
{
  iSerOK != close(hSerPort);
  if (!iSerOK) SerCrash("Problem closing serial port","");
}
void SerPut(char* data)
// Transmits a line followed by CR and LF.
// Caution!  Will wait forever, without registering an error,
// if handshaking signals tell it not to transmit.
{
  DWORD nBytes;
  iSerOK =  nBytes=write(hSerPort,(const void *)data,strlen(data));
  iSerOK &= nBytes=write(hSerPort,"\r\n",2);
  if (!iSerOK) SerCrash("Problem writing to serial port","");
}
void SerGetChar(char* c, int* success)
// Receives a character from the serial port,
// or times out after 10 seconds.
// success = 0 if timeout, 1 if successful
{
  time_t finish;
  finish = time(NULL) + 10;
  *success = 0;
  DWORD nBytes = 0;
  while ((*success == 0) && (time(NULL) < finish)) {
    nBytes=read(hSerPort,c,(size_t)1);
    *success = nBytes;

  }
  if (*success == 0)
    SerCrash("Timed out waiting for serial input","");
}
void SerGet(char* buf, int bufsize)
// Inputs a line from the serial port, stopping at
// end of line, carriage return, timeout, or buffer full.
{
  int bufpos = 0;
  buf[bufpos] = 0;    // initialize empty string
  int bufposmax = bufsize-1;  // maximum subscript
  char c = 0;
  int success = 0;
//
  // Eat any Return or Line Feed characters
  // left over from end of previous line
  //
  do { SerGetChar(&c,&success); }
  while ((success == 1) && (c <= 31));
  //
  // We have now read the first character or timed out.
  // Read characters until any termination condition is met.
  //
  while (1) {
    if (success == 0) return;         // timeout
    if (c == 13) return;              // carriage return
    if (c == 10) return;              // line feed
    if (bufpos >= bufposmax) return;  // buffer full
    buf[bufpos] = c;
    bufpos++;
    buf[bufpos] = 0;  // guarantee validly terminated string
    SerGetChar(&c,&success);
  }
}
void SerGetNum(double* x)
// Reads a floating-point number from the serial port.
{
   char buf[20];
   SerGet(buf,sizeof(buf));
   iSerOK = sscanf(buf,"%lf",x);   // "%lf" = "long float" = double
   if (iSerOK < 1) {
     SerCrash("Problem converting string to number",buf);
     *x = 0.0;
   }
}
// Sample main program to conduct dialogue
// with Agilent 54645D oscilloscope,
// 9600 baud, DTR handshaking
int main()
{
 char b[20];
 double x;
 // Sample dialogue for Agilent 64645D oscilloscope
 SerOpen("/dev/ttyUSB0","RTS");   // note RTS handshaking
 SerPut("*RST");
 SerPut("*CLS");
 SerPut(":SYSTEM:DSP 'Communicating with computer'");
 SerPut(":AUTOSCALE");
 SerPut(":MEASURE:VRMS? ANALOG1");
 SerGetNum(&x);
 printf( "Channel 1 RMS voltage (as number) = %f\n", x );
 // cout << "Channel 1 RMS voltage (as number) = " << x << "\n";
 SerPut(":MEASURE:VPP? ANALOG2");
 SerGet(b,sizeof(b));
 printf( "Channel 2 P-P voltage (as string) = %s\n", b );
 // cout << "Channel 2 P-P voltage (as string) = " << b << "\n";
/*
// Sample dialogue for Agilent 34401A multimeter
 SerOpen("COM1","DTR");   // note DTR handshaking
 SerPut(":SYST:REM");
 SerPut("*RST");
 SerPut("*CLS");
 SerPut(":DISP:TEXT 'OK'");
 SerPut(":MEASURE:VOLT:DC?");
 SerGetNum(&x);
 printf( "Voltage (as number) = %d\n", x );
 // cout << "Voltage (as number) = " << x << "\n";
 SerPut(":MEASURE:VOLT:DC?");
 SerGet(b,sizeof(b));
 printf( "Voltage (as string) = %s\n", b );
 // cout << "Voltage (as string) = " << b << "\n";
*/
 // Say goodbye
 printf( "Press Enter...");
 scanf("\r");
  SerClose();
 return 0;
}