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Add experimental RS-485 support

Browse source 
Many modern RS-485 serial devices such as the ones from FTDI already
operate in RS-485 mode by default and will work with tio out of the box.
However, there are some RS-232/485 devices which need to be switched
from e.g. RS-232 to RS-485 mode to operate accordingly on the physical
level.

This commit implements the switching mechanism and interface required to
enable RS-485 mode. It only works on Linux and with serial devices which
use device drivers that support the Linux RS-485 control interface.

The RS-485 feature is detailed via the following options:

 --rs-485                           Enable RS-485 mode
 --rs-485-config <config>           Set RS-485 configuration

Set the RS-485 configuration using the following key or key value pair
format in the configuration field:

 RTS_ON_SEND=value             Set logical level (0 or 1) for RTS pin when sending
 RTS_AFTER_SEND=value          Set logical level (0 or 1) for RTS pin after sending
 RTS_DELAY_BEFORE_SEND=value   Set RTS delay (ms) before sending
 RTS_DELAY_AFTER_SEND=value    Set RTS delay (ms) after sending
 RX_DURING_TX                  Receive data even while sending data

If defining more than one key or key value pair, they must be comma
separated.

Example use:

 $ tio /dev/ttyUSB0 --rs-485 --rs-r485-config=RTS_DELAY_AFTER_SEND=50,RX_DURING_TX
This commit is contained in:
Martin Lund 2022-09-10 15:20:42 +02:00
parent a58d406a3c
commit ee46686fb6
13 changed files with 351 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

10
src/bash-completion/tio.in
View file

@ -31,6 +31,8 @@ _tio()
-S --socket \
-r --response-wait \
--response-timeout \
--rs-485 \
--rs-485-config \
-x --hexadecimal \
-v --version \
-h --help"
@ -122,6 +124,14 @@ _tio()
COMPREPLY=( $(compgen -W "1 10 100" -- ${cur}) )
return 0
;;
--rs-485)
COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
return 0
;;
--rs-485-config)
COMPREPLY=( $(compgen -W "RTS_ON_SEND RTS_AFTER_SEND RTS_DELAY_BEFORE_SEND RTS_DELAY_AFTER_SEND RX_DURING_TX" -- ${cur}) )
return 0
;;
-x | --hexadecimal)
COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
return 0

17
src/configfile.c
View file

@ -42,6 +42,7 @@
#include "options.h"
#include "error.h"
#include "print.h"
#include "rs485.h"
static struct config_t *c;
@ -264,6 +265,22 @@ static int data_handler(void *user, const char *section, const char *name,
{
option.response_timeout = atoi(value);
}
else if (!strcmp(name, "rs-485"))
{
if (!strcmp(value, "enable"))
{
option.rs485 = true;
}
else if (!strcmp(value, "disable"))
{
option.rs485 = false;
}
}
else if (!strcmp(name, "rs-485-config"))
{
rs485_parse_config(value);
}
}
return 0;
}

7
src/meson.build
View file

@ -14,7 +14,8 @@ tio_sources = [
'configfile.c',
'signals.c',
'socket.c',
'setspeed.c'
'setspeed.c',
'rs485.c'
]
tio_dep = dependency('inih', required: true,
@ -31,6 +32,10 @@ if enable_iossiospeed
tio_c_args += '-DHAVE_IOSSIOSPEED'
endif
if enable_rs485
tio_c_args += '-DHAVE_RS485'
endif
executable('tio',
tio_sources,
c_args: tio_c_args,

19
src/options.c
View file

@ -35,6 +35,7 @@
#include "misc.h"
#include "print.h"
#include "tty.h"
#include "rs485.h"
enum opt_t
{
@ -44,6 +45,8 @@ enum opt_t
OPT_LOG_STRIP,
OPT_LINE_PULSE_DURATION,
OPT_RESPONSE_TIMEOUT,
OPT_RS485,
OPT_RS485_CONFIG,
};
/* Default options */
@ -78,6 +81,10 @@ struct option_t option =
.response_wait = false,
.response_timeout = 100,
.mute = false,
.rs485 = false,
.rs485_config_flags = 0,
.rs485_delay_rts_before_send = -1,
.rs485_delay_rts_after_send = -1,
};
void print_help(char *argv[])
@ -109,6 +116,8 @@ void print_help(char *argv[])
printf(" -x, --hexadecimal Enable hexadecimal mode\n");
printf(" -r, --response-wait Wait for line response then quit\n");
printf(" --response-timeout <ms> Response timeout (default: 100)\n");
printf(" --rs-485 Enable RS-485 mode\n");
printf(" --rs-485-config <config> Set RS-485 configuration\n");
printf(" -v, --version Display version\n");
printf(" -h, --help Display help\n");
printf("\n");
@ -295,6 +304,8 @@ void options_parse(int argc, char *argv[])
{"hexadecimal", no_argument, 0, 'x' },
{"response-wait", no_argument, 0, 'r' },
{"response-timeout", required_argument, 0, OPT_RESPONSE_TIMEOUT },
{"rs-485", no_argument, 0, OPT_RS485 },
{"rs-485-config", required_argument, 0, OPT_RS485_CONFIG },
{"version", no_argument, 0, 'v' },
{"help", no_argument, 0, 'h' },
{0, 0, 0, 0 }
@ -437,6 +448,14 @@ void options_parse(int argc, char *argv[])
option.response_timeout = string_to_long(optarg);
break;
case OPT_RS485:
option.rs485 = true;
break;
case OPT_RS485_CONFIG:
rs485_parse_config(optarg);
break;
case 'v':
printf("tio v%s\n", VERSION);
exit(EXIT_SUCCESS);

5
src/options.h
View file

@ -21,6 +21,7 @@
#pragma once
#include <stdint.h>
#include <stdbool.h>
#include <limits.h>
#include <termios.h>
@ -70,6 +71,10 @@ struct option_t
bool response_wait;
int response_timeout;
bool mute;
bool rs485;
uint32_t rs485_config_flags;
int32_t rs485_delay_rts_before_send;
int32_t rs485_delay_rts_after_send;
};
extern struct option_t option;

1
src/print.h
View file

@ -21,6 +21,7 @@
#pragma once
#include <stdio.h>
#include <stdbool.h>
#include "misc.h"
#include "error.h"

200
src/rs485.c Normal file
View file

@ -0,0 +1,200 @@
/*
* tio - a simple serial device I/O tool
*
* Copyright (c) 2022 Martin Lund
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <stdbool.h>
#include "options.h"
#include "print.h"
#include "error.h"
#ifdef HAVE_RS485
#include <linux/serial.h>
static struct serial_rs485 rs485_config_saved;
static struct serial_rs485 rs485_config;
static bool rs485_config_written = false;
void rs485_parse_config(const char *arg)
{
bool token_found = true;
char *token = NULL;
char *buffer = strdup(arg);
while (token_found == true)
{
if (token == NULL)
{
token = strtok(buffer,",");
}
else
{
token = strtok(NULL, ",");
}
if (token != NULL)
{
char keyname[31];
unsigned int value;
sscanf(token, "%30[^=]=%d", keyname, &value);
if (!strcmp(keyname, "RTS_ON_SEND"))
{
if (value)
{
/* Set logical level for RTS pin equal to 1 when sending */
option.rs485_config_flags |= SER_RS485_RTS_ON_SEND;
}
else
{
/* Set logical level for RTS pin equal to 0 when sending */
option.rs485_config_flags &= ~(SER_RS485_RTS_ON_SEND);
}
}
else if (!strcmp(keyname, "RTS_AFTER_SEND"))
{
if (value)
{
/* Set logical level for RTS pin equal to 1 after sending */
option.rs485_config_flags |= SER_RS485_RTS_AFTER_SEND;
}
else
{
/* Set logical level for RTS pin equal to 0 after sending */
option.rs485_config_flags &= ~(SER_RS485_RTS_AFTER_SEND);
}
}
else if (!strcmp(keyname, "RTS_DELAY_BEFORE_SEND"))
{
/* Set RTS delay before send */
option.rs485_delay_rts_before_send = value;
}
else if (!strcmp(keyname, "RTS_DELAY_AFTER_SEND"))
{
/* Set RTS delay after send */
option.rs485_delay_rts_after_send = value;
}
else if (!strcmp(keyname, "RX_DURING_TX"))
{
/* Receive data even while sending data */
option.rs485_config_flags |= SER_RS485_RX_DURING_TX;
}
}
else
{
token_found = false;
}
}
free(buffer);
}
void rs485_print_config(void)
{
tio_printf(" RS-485 Configuration:");
tio_printf(" RTS_ON_SEND: %s", (rs485_config.flags & SER_RS485_RTS_ON_SEND) ? "high" : "low");
tio_printf(" RTS_AFTER_SEND: %s", (rs485_config.flags & SER_RS485_RTS_AFTER_SEND) ? "high" : "low");
tio_printf(" RTS_DELAY_BEFORE_SEND = %d", rs485_config.delay_rts_before_send);
tio_printf(" RTS_DELAY_AFTER_SEND = %d", rs485_config.delay_rts_after_send);
tio_printf(" RX_DURING_TX: %s", (rs485_config.flags & SER_RS485_RX_DURING_TX) ? "enabled" : "disabled");
}
int rs485_mode_enable(int fd)
{
/* Save existing RS-485 configuration */
ioctl (fd, TIOCGRS485, &rs485_config_saved);
/* Prepare new RS-485 configuration */
rs485_config.flags = SER_RS485_ENABLED;
rs485_config.flags |= option.rs485_config_flags;
if (option.rs485_delay_rts_before_send > 0)
{
rs485_config.delay_rts_before_send = option.rs485_delay_rts_before_send;
}
else
{
rs485_config.delay_rts_before_send = rs485_config_saved.delay_rts_before_send;
}
if (option.rs485_delay_rts_after_send > 0)
{
rs485_config.delay_rts_after_send = option.rs485_delay_rts_after_send;
}
else
{
rs485_config.delay_rts_after_send = rs485_config_saved.delay_rts_after_send;
}
/* Write new RS-485 configuration */
if (ioctl(fd, TIOCSRS485, &rs485_config) < 0)
{
tio_warning_printf("RS-485 mode is not supported by your device (%s)", strerror(errno));
return -1;
}
rs485_config_written = true;
return 0;
}
void rs485_mode_restore(int fd)
{
if (rs485_config_written)
{
/* Write saved RS-485 configuration */
if (ioctl(fd, TIOCSRS485, &rs485_config_saved) < 0)
{
tio_warning_printf("TIOCGRS485 ioctl failed (%s)", strerror(errno));
}
}
}
#else
void rs485_parse_config(const char *arg)
{
UNUSED(arg);
return;
}
void rs485_print_config(void)
{
return;
}
int rs485_mode_enable(int fd)
{
UNUSED(fd);
tio_error_printf("RS485 mode is not supported on your system");
exit(EXIT_FAILURE);
}
void rs485_mode_restore(int fd)
{
UNUSED(fd);
return;
}
#endif

27
src/rs485.h Normal file
View file

@ -0,0 +1,27 @@
/*
* tio - a simple serial device I/O tool
*
* Copyright (c) 2022 Martin Lund
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#pragma once
void rs485_parse_config(const char *arg);
int rs485_mode_enable(int fd);
void rs485_mode_restore(int fd);
void rs485_print_config(void);

17
src/tty.c
View file

@ -50,6 +50,7 @@
#include "error.h"
#include "socket.h"
#include "setspeed.h"
#include "rs485.h"
#ifdef __APPLE__
#define PATH_SERIAL_DEVICES "/dev/"
@ -456,6 +457,10 @@ void handle_command_sequence(char input_char, char previous_char, char *output_c
tio_printf("Configuration:");
config_file_print();
options_print();
if (option.rs485)
{
rs485_print_config();
}
break;
case KEY_E:
@ -947,6 +952,12 @@ void tty_restore(void)
{
tcsetattr(fd, TCSANOW, &tio_old);
if (option.rs485)
{
/* Restore original RS-485 mode */
rs485_mode_restore(fd);
}
if (connected)
{
tty_disconnect();
@ -1081,6 +1092,12 @@ int tty_connect(void)
}
#endif
/* Manage RS-485 mode */
if (option.rs485)
{
rs485_mode_enable(fd);
}
/* Make sure we restore tty settings on exit */
if (first)
{