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/*
* Copyright 2014-present Facebook. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <getopt.h>
#include "modbus.h"
void usage() {
fprintf(stderr,
"modbussim [-v] [-t <tty>] [-g <gpio>] modbus_request modbus_reply\n"
"\ttty defaults to %s\n"
"\tgpio defaults to %d\n"
"\tmodbus request/reply should be specified in hex\n"
"\teg:\ta40300000008\n",
DEFAULT_TTY, DEFAULT_GPIO);
exit(1);
}
int main(int argc, char **argv) {
int error = 0;
int fd;
struct termios tio;
char gpio_filename[255];
int gpio_fd = 0;
int gpio_n = DEFAULT_GPIO;
char *tty = DEFAULT_TTY;
char *modbus_cmd = NULL;
char *modbus_reply = NULL;
size_t cmd_len = 0;
size_t reply_len = 0;
verbose = 0;
int opt;
while((opt = getopt(argc, argv, "t:g:v"))) {
if (opt == -1) break;
switch (opt) {
case 't':
tty = optarg;
break;
case 'g':
gpio_n = atoi(optarg);
break;
case 'v':
verbose = 1;
break;
default:
usage();
break;
}
}
if(optind < argc) {
modbus_cmd = argv[optind++];
modbus_reply = argv[optind++];
}
if(modbus_cmd == NULL || modbus_reply == NULL) {
usage();
}
if (verbose)
fprintf(stderr, "[*] Opening TTY\n");
fd = open(tty, O_RDWR | O_NOCTTY);
CHECK(fd);
if (verbose)
fprintf(stderr, "[*] Opening GPIO %d\n", gpio_n);
snprintf(gpio_filename, 255, "/sys/class/gpio/gpio%d/value", gpio_n);
gpio_fd = open(gpio_filename, O_WRONLY | O_SYNC);
CHECK(gpio_fd);
if (verbose)
fprintf(stderr, "[*] Setting TTY flags!\n");
memset(&tio, 0, sizeof(tio));
cfsetspeed(&tio,B19200);
tio.c_cflag |= PARENB;
tio.c_cflag |= CLOCAL;
tio.c_cflag |= CS8;
tio.c_iflag |= INPCK;
tio.c_cc[VMIN] = 1;
tio.c_cc[VTIME] = 0;
CHECK(tcsetattr(fd,TCSANOW,&tio));
//convert hex to bytes
cmd_len = strlen(modbus_cmd);
if(cmd_len < 2) {
fprintf(stderr, "Command too short!\n");
exit(1);
}
decode_hex_in_place(modbus_cmd, &cmd_len);
append_modbus_crc16(modbus_cmd, &cmd_len);
if (verbose) {
fprintf(stderr, "expect: ");
print_hex(stderr, modbus_cmd, cmd_len);
fprintf(stderr, "\n");
}
reply_len = strlen(modbus_reply);
decode_hex_in_place(modbus_reply, &reply_len);
append_modbus_crc16(modbus_reply, &reply_len);
// print full expected reply
if (verbose) {
fprintf(stderr, "reply: ");
print_hex(stderr, modbus_reply, reply_len);
fprintf(stderr, "\n");
}
// Enable UART read
tio.c_cflag |= CREAD;
CHECK(tcsetattr(fd,TCSANOW,&tio));
gpio_off(gpio_fd);
if(verbose)
fprintf(stderr, "[*] Wait for matching command...\n");
char modbus_buf[255];
size_t mb_pos;
wait_for_command:
mb_pos = read_wait(fd, modbus_buf, sizeof(modbus_buf), 30000);
if(mb_pos >= 4) {
printf("Received: ");
print_hex(stdout, modbus_buf, mb_pos);
uint16_t crc = modbus_crc16(modbus_buf, mb_pos - 2);
if((modbus_buf[mb_pos - 2] == (crc >> 8)) &&
(modbus_buf[mb_pos - 1] == (crc & 0x00FF))) {
if(verbose)
fprintf(stderr, "CRC OK!\n");
if(memcmp(modbus_buf, modbus_cmd, cmd_len) == 0) {
fprintf(stderr, "Command matched!\n");
} else {
fprintf(stderr, "Got modbus cmd that didn't match.\n");
goto wait_for_command;
}
} else {
fprintf(stderr, "Got data that failed modbus CRC.\n");
goto wait_for_command;
}
} else {
goto wait_for_command;
}
if (verbose)
fprintf(stderr, "[*] Writing reply!\n");
// Disable UART read
tio.c_cflag &= ~CREAD;
CHECK(tcsetattr(fd,TCSANOW,&tio));
// gpio on, write, wait, gpio off
gpio_on(gpio_fd);
write(fd, modbus_reply, reply_len);
waitfd(fd);
gpio_off(gpio_fd);
cleanup:
if(error != 0) {
error = 1;
fprintf(stderr, "%s\n", strerror(errno));
}
return error;
}
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