Simple HALCON (Linux) program for ICube to grab a JPEG image on SIGUSR1.

grab.c

#include <signal.h>
#include "HalconC.h"

#ifndef NO_EXPORT_MAIN

int quit;
Htuple AcqHandle;

void start()
{
    Htuple TTemp[100];
    int i, SP = 0;

    create_tuple(&AcqHandle, 0);

    create_tuple_s(&TTemp[SP++],"ICube");
    create_tuple_i(&TTemp[SP++],1280);
    create_tuple_i(&TTemp[SP++],1024);
    create_tuple_i(&TTemp[SP++],0);
    create_tuple_i(&TTemp[SP++],0);
    create_tuple_i(&TTemp[SP++],0);
    create_tuple_i(&TTemp[SP++],0);
    create_tuple_s(&TTemp[SP++],"default");
    create_tuple_i(&TTemp[SP++],-1);
    create_tuple_s(&TTemp[SP++],"default");
    create_tuple_i(&TTemp[SP++],-1);
    create_tuple_s(&TTemp[SP++],"false");
    create_tuple_s(&TTemp[SP++],"default");
    create_tuple_s(&TTemp[SP++],"");
    create_tuple_i(&TTemp[SP++],0);
    create_tuple_i(&TTemp[SP++],-1);
    destroy_tuple(AcqHandle);
    T_open_framegrabber(TTemp[SP-16], TTemp[SP-15], TTemp[SP-14], TTemp[SP-13], TTemp[SP-12], TTemp[SP-11], TTemp[SP-10], TTemp[SP-9], TTemp[SP-8], TTemp[SP-7], TTemp[SP-6], TTemp[SP-5], TTemp[SP-4], TTemp[SP-3], TTemp[SP-2], TTemp[SP-1], &AcqHandle);
    while(SP)
        destroy_tuple(TTemp[--SP]);
}

void handler(int signum)
{
    if(signum == SIGUSR1)
    {
        Hobject Image;
        gen_empty_obj(&Image);

        clear_obj(Image);
        T_grab_image(&Image, AcqHandle);

        write_image(Image, "jpeg 85", 0, "image.jpg");

        clear_obj(Image);
    }
    else if(signum == SIGTERM)
    {
        T_close_framegrabber(AcqHandle);
        quit = 1;
    }
}

#ifndef NO_EXPORT_APP_MAIN
int main(int argc, char * argv[])
{
    struct sigaction new;
    new.sa_handler = handler;
    sigemptyset(&new.sa_mask);
    new.sa_flags = 0;

    sigaction (SIGUSR1, &new, NULL);
    sigaction (SIGTERM, &new, NULL);

    quit = 0;
    start();

    while(!quit)
        pause();

    return 0;
}
#endif

#endif

Assuming your HALCON install is the 32-bit version, and in /opt/halcon, this compiles with:

gcc -I/opt/halcon/include -L/opt/halcon/lib/x86sse2-linux2.4-gcc40 -lhalcon -lhalconc -m32 -o grab grab.c