When building with Visual Studio I got a warning in zeagle_n2ition3.c.  The following code looks a bit suspicious to me.

static device_status_t
zeagle_n2ition3_init (zeagle_n2ition3_device_t *device)
{
    unsigned char answer[6 + 13] = {0};
    unsigned char command[6] = {0x02, 0x01, 0x00, 0x41, 0xBF, 0x03};
    command[11] = ~checksum_add_uint8 (command + 3, 8, 0x00) + 1;

    return zeagle_n2ition3_packet (device, command, sizeof (command), answer, sizeof (answer));
}

You are setting command[11] to a value when there are only 6 elements in command.