This  page will demonstrate how to send and receive data from the ADR112   or any other ADR interface,  using Linux gcc programmes. It shows the commands used to configure the serial port, send data out through the serial port, and receive data through the serial port.

Additional help is available from the Linux HowTo documents found at a variety of locations around the web (hint: use a search engine). The man pages of your Linux system are invaluable as well. I make no effort to explain all of the parameters used in the various API calls. Read The Famous Manual.

This page is divided into several sections. The first section presents the source code with brief usage details. The second section shows pictorial examples and screen shots. Some troubleshooting hints are given in the second section. The third section describes some details (skip it if the first two sections provide what you need.)

Linux Version

I tested this program using Redhat 7.3, however I believe this code will operate correctly under all recent Linux kernels (your mileage may vary). The code was compiled with version 2.96-110 of the gcc compiler. Any recent vintage of the gcc compiler should be fine.

Source Code

There are four files needed to compile the Linux example.

• adrport.h
• adrport.c
• adrserial.c
• Makefile

adrport.h

// adrport.h
// Copyright MMI, MMII by Sisusypro Incorporated

int OpenAdrPort (char* sPortNumber);
int WriteAdrPort(char* psOutput);
int ReadAdrPort(char* psResponse, int iMax);
void CloseAdrPort();
    

adrport.c

// adrport.c - Serial Port Handler
// Copyright MMI, MMII by Sisusypro Incorporated

// Permission is hereby granted to freely copy, 
// modify, utilize and distribute this example in 
// whatever manner you desire without restriction.

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <string.h>
#include <errno.h>
#include "adrport.h"
static int fd = 0;

// opens the serial port
// return code:
//   > 0 = fd for the port
//   -1 = open failed
int OpenAdrPort(char* sPortNumber)
{
    char sPortName[64];
    printf("in OpenAdrPort port#=%s\n", sPortNumber);
    sprintf(sPortName, "/dev/ttyS%s", sPortNumber);
    printf("sPortName=%s\n", sPortName);

    // make sure port is closed
    CloseAdrPort(fd);

    fd = open(sPortName, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd < 0)
    {
        printf("open error %d %s\n", errno, strerror(errno));
    }
    else
    {
        struct termios my_termios;
        printf("fd is %d\n", fd);
        tcgetattr(fd, &my_termios);
        // NOTE: you may want to save the port attributes 
        //       here so that you can restore them later
        printf("old cflag=%08x\n", my_termios.c_cflag);
        printf("old oflag=%08x\n", my_termios.c_oflag);
        printf("old iflag=%08x\n", my_termios.c_iflag);
        printf("old lflag=%08x\n", my_termios.c_lflag);
        printf("old line=%02x\n", my_termios.c_line);

        tcflush(fd, TCIFLUSH);
        
        my_termios.c_cflag = B9600 | CS8 |CREAD | CLOCAL | HUPCL;
        
        cfsetospeed(&my_termios, B9600);
        tcsetattr(fd, TCSANOW, &my_termios);
 
        printf("new cflag=%08x\n", my_termios.c_cflag);
        printf("new oflag=%08x\n", my_termios.c_oflag);
        printf("new iflag=%08x\n", my_termios.c_iflag);
        printf("new lflag=%08x\n", my_termios.c_lflag);
        printf("new line=%02x\n", my_termios.c_line);
    } // end if
    return fd;
} // end OpenAdrPort

// writes zero terminated string to the serial port
// return code:
//   >= 0 = number of characters written
//   -1 = write failed
int WriteAdrPort(char* psOutput)
{
    int iOut;
    if (fd < 1)
    {
        printf(" port is not open\n");
        return -1;
    } // end if
    iOut = write(fd, psOutput, strlen(psOutput));
    if (iOut < 0)
    {
        printf("write error %d %s\n", errno, strerror(errno));
    }
    else
    {
    	printf("wrote %d chars: %s\n", iOut, psOutput);
    } // end if
    return iOut;
} // end WriteAdrPort

// read string from the serial port
// return code:
//   >= 0 = number of characters read
//   -1 = read failed
int ReadAdrPort(char* psResponse, int iMax)
{
    int iIn;
    printf("in ReadAdrPort iMax=%d\n", iMax);
    if (fd < 1)
    {
        printf(" port is not open\n");
        return -1;
    } // end if
    strncpy (psResponse, "N/A", iMax<4?iMax:4);
    iIn = read(fd, psResponse, iMax-1);
    if (iIn < 0)
    {
    	if (errno == EAGAIN)
    	{
		return 0; // assume that command generated no response
	}
	else
	{
		printf("read error %d %s\n", errno, strerror(errno));
	} // end if
    }
    else
    {
    	psResponse[iIn<iMax?iIn:iMax] = '\0';
	    printf("read %d chars: %s\n", iIn, psResponse);
    } // end if

    return iIn;
} // end ReadAdrPort

// closes the serial port
void CloseAdrPort()
{
	// you may want to restore the saved port attributes
    if (fd > 0)
    {
        close(fd);
    } // end if
} // end CloseAdrPort
    

adrserial.c

// adrserial.c - Serial Port Test Example                  
// Copyright MMII by Sisusypro Incorporated

// WARNING: Example only. Lacks error checking!
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "adrport.h"  
            
// this is the mainline thingee
int main(int argc, char *argv[]) 
{ 
	char sCmd[254];
	char sResult[254];
	if (argc < 2 || argc > 2)
	{
		printf("adrserial needs 1 parameter for the serial port\n");
		printf("  ie. use 'adrserial 0' to connect to /dev/ttyS0\n");
		return 0;
	} // end if
	printf("Type q to quit.\n\n");
	if (OpenAdrPort(argv[1]) < 0) return 0;
	while (1)
	{
		int iSpot;
		
		printf("?:");
		gets(sCmd);
		if (sCmd[0] == 'q' || sCmd[0] == 'Q') return 0;
		iSpot = strlen(sCmd);
		sCmd[iSpot] = 0x0d; // stick a <CR> after the command
		sCmd[iSpot+1] = 0x00; // terminate the string properly
		if (WriteAdrPort(sCmd) < 0) return 0;
		sleep(1); // give the ADR card some time to respond
		if (ReadAdrPort(sResult,254) > 0)
		{
			printf("****Response is %s\n", sResult);
		} // end if
	} // end while
	
	CloseAdrPort();

} // end main
    

Makefile

CFLAGS=-g -Wall 
adrserial: adrserial.c adrport.c
	gcc -g -c -Wall adrserial.c -o adrserial.o
	gcc -g -c -Wall adrport.c -o adrport.o
	gcc adrport.o adrserial.o -o adrserial
    

Ontrak will send you a tarred and gzipped version of the above files (see bottom of this page), but it includes nothing beyond what is listed above.

          chmod o+rw /dev/ttyS0
    

        ./adrserial 0
    

    ./adrserial 0
    

    find /usr/include -exec grep -l 'EAGAIN' {} \;
    

    gunzip LinuxEg.tar.gz
    

    tar -xvf LinuxEg.tar
    

 Back to Programming Page

NEWS         PRODUCTS         PROGRAMMING          APPLICATIONS          CUSTOM DESIGN          ORDERING          HOME

TestPoint is a trademark of Capital Equipment Corp.   
LabVIEW is a trademark of National Instruments.
Visual BASIC is a trademark of Microsoft Corporation

Copyright © 2002 ONTRAK CONTROL SYSTEMS 764 Notre Dame Ave, Unit #1 , Sudbury, Ontario, CANADA P3A 2T2  
"Quality serial Data Acquisition Interfaces"           PH. (705) 671-2652 FAX (705) 671-6127