I bought myself a couple of temper USB sensors from [[http://dx.com/p/temper-usb-thermometer-temperature-recorder-for-pc-laptop-81105?item=2|DX]] and found pcsensor.c which could read from the device. I bought 2 and had 2 more on the way, but the code only supported 1 device. Fortunately the code was open source, so I slightly modified it.

Use -d<int> to specify a device. Examples:
  * device0: ./pcsensor -c -d0 -l1
  * device1: ./pcsensor -c -d1 -l1

Thanks to the people who made this code.

__WARNING: Only tested with temper 1.2__

Here's the code with my modifications:
<file c pcsensor.c>
/*
 * pcsensor.c by Juan Carlos Perez (c) 2011 (cray@isp-sl.com)
 * based on Temper.c by Robert Kavaler (c) 2009 (relavak.com)
 * All rights reserved.
 *
 * Temper driver for linux. This program can be compiled either as a library
 * or as a standalone program (-DUNIT_TEST). The driver will work with some
 * TEMPer usb devices from RDing (www.PCsensor.com).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 * 
 * THIS SOFTWARE IS PROVIDED BY Juan Carlos Perez ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL Robert kavaler BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */



#include <usb.h>
#include <stdio.h>
#include <time.h>

#include <string.h>
#include <errno.h>
#include <signal.h> 
 
 
#define VERSION "1.0.0"
 
#define VENDOR_ID  0x0c45
#define PRODUCT_ID 0x7401
 
#define INTERFACE1 0x00
#define INTERFACE2 0x01
 
const static int reqIntLen=8;
const static int reqBulkLen=8;
const static int endpoint_Int_in=0x82; /* endpoint 0x81 address for IN */
const static int endpoint_Int_out=0x00; /* endpoint 1 address for OUT */
const static int endpoint_Bulk_in=0x82; /* endpoint 0x81 address for IN */
const static int endpoint_Bulk_out=0x00; /* endpoint 1 address for OUT */
const static int timeout=5000; /* timeout in ms */
 
const static char uTemperatura[] = { 0x01, 0x80, 0x33, 0x01, 0x00, 0x00, 0x00, 0x00 };
const static char uIni1[] = { 0x01, 0x82, 0x77, 0x01, 0x00, 0x00, 0x00, 0x00 };
const static char uIni2[] = { 0x01, 0x86, 0xff, 0x01, 0x00, 0x00, 0x00, 0x00 };

static int bsalir=1;
static int debug=0;
static int devid=0;
static int seconds=5;
static int formato=0;
static int mrtg=0;
static int calibration=0;


void bad(const char *why) {
        fprintf(stderr,"Fatal error> %s\n",why);
        exit(17);
}
 
 
usb_dev_handle *find_lvr_winusb();
 
void usb_detach(usb_dev_handle *lvr_winusb, int iInterface) {
        int ret;
 
        ret = usb_detach_kernel_driver_np(lvr_winusb, iInterface);
        if(ret) {
                if(errno == ENODATA) {
                        if(debug) {
                                printf("Device already detached\n");
                        }
                } else {
                        if(debug) {
                                printf("Detach failed: %s[%d]\n",
                                       strerror(errno), errno);
                                printf("Continuing anyway\n");
                        }
                }
        } else {
                if(debug) {
                        printf("detach successful\n");
                }
        }
} 

usb_dev_handle* setup_libusb_access() {
     usb_dev_handle *lvr_winusb;

     if(debug) {
        usb_set_debug(255);
     } else {
        usb_set_debug(0);
     }
     usb_init();
     usb_find_busses();
     usb_find_devices();
             
 
     if(!(lvr_winusb = find_lvr_winusb())) {
                printf("Couldn't find the USB device, Exiting\n");
                return NULL;
        }
        
        
        usb_detach(lvr_winusb, INTERFACE1);
        

        usb_detach(lvr_winusb, INTERFACE2);
        
 
        if (usb_set_configuration(lvr_winusb, 0x01) < 0) {
                printf("Could not set configuration 1\n");
                return NULL;
        }
 

        // Microdia tiene 2 interfaces
        if (usb_claim_interface(lvr_winusb, INTERFACE1) < 0) {
                printf("Could not claim interface\n");
                return NULL;
        }
 
        if (usb_claim_interface(lvr_winusb, INTERFACE2) < 0) {
                printf("Could not claim interface\n");
                return NULL;
        }
 
        return lvr_winusb;
}
 
 
 
usb_dev_handle *find_lvr_winusb() {
 
     int loopval = 0;
     struct usb_bus *bus;
        struct usb_device *dev;
 
        for (bus = usb_busses; bus; bus = bus->next) {
        for (dev = bus->devices; dev; dev = dev->next) {
                        if (dev->descriptor.idVendor == VENDOR_ID && 
                                dev->descriptor.idProduct == PRODUCT_ID ) {
                                usb_dev_handle *handle;
                                if (loopval != devid) {
                                        loopval++;
                                        if (debug) {
                                                printf("Increased loopval - loopval: %i - devid: %i\n", loopval, devid);
                                        }
                                } else {
                                        if(debug) {
                                          printf("lvr_winusb with Vendor Id: %x and Product Id: %x found.\n", VENDOR_ID, PRODUCT_ID);
                                        }

                                        if (!(handle = usb_open(dev))) {
                                                printf("Could not open USB device\n");
                                                return NULL;
                                        }
                                        return handle;
                                }
                        }
                }
        }
        return NULL;
}
 
 
void ini_control_transfer(usb_dev_handle *dev) {
    int r,i;

    char question[] = { 0x01,0x01 };

    r = usb_control_msg(dev, 0x21, 0x09, 0x0201, 0x00, (char *) question, 2, timeout);
    if( r < 0 )
    {
          perror("USB control write"); bad("USB write failed"); 
    }


    if(debug) {
      for (i=0;i<reqIntLen; i++) printf("%02x ",question[i] & 0xFF);
      printf("\n");
    }
}
 
void control_transfer(usb_dev_handle *dev, const char *pquestion) {
    int r,i;

    char question[reqIntLen];
    
    memcpy(question, pquestion, sizeof question);

    r = usb_control_msg(dev, 0x21, 0x09, 0x0200, 0x01, (char *) question, reqIntLen, timeout);
    if( r < 0 )
    {
          perror("USB control write"); bad("USB write failed"); 
    }

    if(debug) {
        for (i=0;i<reqIntLen; i++) printf("%02x ",question[i]  & 0xFF);
        printf("\n");
    }
}

void interrupt_transfer(usb_dev_handle *dev) {
 
    int r,i;
    char answer[reqIntLen];
    char question[reqIntLen];
    for (i=0;i<reqIntLen; i++) question[i]=i;
    r = usb_interrupt_write(dev, endpoint_Int_out, question, reqIntLen, timeout);
    if( r < 0 )
    {
          perror("USB interrupt write"); bad("USB write failed"); 
    }
    r = usb_interrupt_read(dev, endpoint_Int_in, answer, reqIntLen, timeout);
    if( r != reqIntLen )
    {
          perror("USB interrupt read"); bad("USB read failed"); 
    }

    if(debug) {
       for (i=0;i<reqIntLen; i++) printf("%i, %i, \n",question[i],answer[i]);
    }
 
    usb_release_interface(dev, 0);
}

void interrupt_read(usb_dev_handle *dev) {
 
    int r,i;
    unsigned char answer[reqIntLen];
    bzero(answer, reqIntLen);
    
    r = usb_interrupt_read(dev, 0x82, answer, reqIntLen, timeout);
    if( r != reqIntLen )
    {
          perror("USB interrupt read"); bad("USB read failed"); 
    }

    if(debug) {
       for (i=0;i<reqIntLen; i++) printf("%02x ",answer[i]  & 0xFF);
    
       printf("\n");
    }
}

void interrupt_read_temperatura(usb_dev_handle *dev, float *tempC) {
 
    int r,i, temperature;
    unsigned char answer[reqIntLen];
    bzero(answer, reqIntLen);
    
    r = usb_interrupt_read(dev, 0x82, answer, reqIntLen, timeout);
    if( r != reqIntLen )
    {
          perror("USB interrupt read"); bad("USB read failed"); 
    }


    if(debug) {
      for (i=0;i<reqIntLen; i++) printf("%02x ",answer[i]  & 0xFF);
    
      printf("\n");
    }
    
    temperature = (answer[3] & 0xFF) + (answer[2] << 8);
    temperature += calibration;
    *tempC = temperature * (125.0 / 32000.0);

}

void bulk_transfer(usb_dev_handle *dev) {
 
    int r,i;
    char answer[reqBulkLen];

    r = usb_bulk_write(dev, endpoint_Bulk_out, NULL, 0, timeout);
    if( r < 0 )
    {
          perror("USB bulk write"); bad("USB write failed"); 
    }
    r = usb_bulk_read(dev, endpoint_Bulk_in, answer, reqBulkLen, timeout);
    if( r != reqBulkLen )
    {
          perror("USB bulk read"); bad("USB read failed"); 
    }


    if(debug) {
      for (i=0;i<reqBulkLen; i++) printf("%02x ",answer[i]  & 0xFF);
    }
 
    usb_release_interface(dev, 0);
}
 

void ex_program(int sig) {
      bsalir=1;
 
      (void) signal(SIGINT, SIG_DFL);
}
 
int main( int argc, char **argv) {
 
     usb_dev_handle *lvr_winusb = NULL;
     float tempc;
     int c;
     struct tm *local;
     time_t t;

     while ((c = getopt (argc, argv, "mfcvhl::a:d:")) != -1)
     switch (c)
       {
       case 'v':
         debug = 1;
         break;
       case 'd':
         if (!sscanf(optarg,"%i",&devid)==1) {
           printf("Error: ' %s' is not a valid deviceid.\n", optarg);
           exit(EXIT_FAILURE);
         }
         break;
       case 'c':
         formato=1; //Celsius
         break;
       case 'f':
         formato=2; //Fahrenheit
         break;
       case 'm':
         mrtg=1;
         break;
       case 'l':
         if (optarg!=NULL){
           if (!sscanf(optarg,"%i",&seconds)==1) {
             fprintf (stderr, "Error: '%s' is not numeric.\n", optarg);
             exit(EXIT_FAILURE);
           } else {           
              bsalir = 0;
              break;
           }
         } else {
           bsalir = 0;
           seconds = 5;
           break;
         }
       case 'a':
         if (!sscanf(optarg,"%i",&calibration)==1) {
             fprintf (stderr, "Error: '%s' is not numeric.\n", optarg);
             exit(EXIT_FAILURE);
         } else {           
              break;
         }
       case '?':
       case 'h':
         printf("pcsensor version %s\n",VERSION);
         printf("      Aviable options:\n");
         printf("          -h help\n");
         printf("          -v verbose\n");
         printf("          -l[n] loop every 'n' seconds, default value is 5s\n");
         printf("          -d[n] use device 'n' instead of the first one found\n");
         printf("          -c output only in Celsius\n");
         printf("          -f output only in Fahrenheit\n");
         printf("          -a[n] increase or decrease temperature in 'n' degrees for device calibration\n");
         printf("          -m output for mrtg integration\n");
  
         exit(EXIT_FAILURE);
       default:
         if (isprint (optopt))
           fprintf (stderr, "Unknown option `-%c'.\n", optopt);
         else
           fprintf (stderr,
                    "Unknown option character `\\x%x'.\n",
                    optopt);
         exit(EXIT_FAILURE);
       }

     if (optind < argc) {
        fprintf(stderr, "Non-option ARGV-elements, try -h for help.\n");
        exit(EXIT_FAILURE);
     }
 
     if ((lvr_winusb = setup_libusb_access()) == NULL) {
         exit(EXIT_FAILURE);
     } 

     (void) signal(SIGINT, ex_program);

     ini_control_transfer(lvr_winusb);
      
     control_transfer(lvr_winusb, uTemperatura );
     interrupt_read(lvr_winusb);
 
     control_transfer(lvr_winusb, uIni1 );
     interrupt_read(lvr_winusb);
 
     control_transfer(lvr_winusb, uIni2 );
     interrupt_read(lvr_winusb);
     interrupt_read(lvr_winusb);


 
     do {
           control_transfer(lvr_winusb, uTemperatura );
           interrupt_read_temperatura(lvr_winusb, &tempc);

           t = time(NULL);
           local = localtime(&t);

           if (mrtg) {
              if (formato==2) {
                  printf("%.2f\n", (9.0 / 5.0 * tempc + 32.0));
                  printf("%.2f\n", (9.0 / 5.0 * tempc + 32.0));
              } else {
                  printf("%.2f\n", tempc);
                  printf("%.2f\n", tempc);
              }
              
              printf("%02d:%02d\n", 
                          local->tm_hour,
                          local->tm_min);

              printf("pcsensor\n");
           } else {
              printf("%04d/%02d/%02d %02d:%02d:%02d ", 
                          local->tm_year +1900, 
                          local->tm_mon + 1, 
                          local->tm_mday,
                          local->tm_hour,
                          local->tm_min,
                          local->tm_sec);

              if (formato==2) {
                  printf("Temperature %.2fF\n", (9.0 / 5.0 * tempc + 32.0));
              } else if (formato==1) {
                  printf("Temperature %.2fC\n", tempc);
              } else {
                  printf("Temperature %.2fF %.2fC\n", (9.0 / 5.0 * tempc + 32.0), tempc);
              }
           }
           
           if (!bsalir)
              sleep(seconds);
     } while (!bsalir);
                                       
     usb_release_interface(lvr_winusb, INTERFACE1);
     usb_release_interface(lvr_winusb, INTERFACE2);
     
     usb_close(lvr_winusb); 
      
     return 0; 
}
</file>