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modbus.c
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modbus.c
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/*
modbus.c - a lightweigth ModBus implementation
Part of grblHAL
Copyright (c) 2020-2021 Terje Io
except modbus_CRC16x which is Copyright (c) 2006 Christian Walter <wolti@sil.at>
Lifted from his FreeModbus Libary
Grbl 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 3 of the License, or
(at your option) any later version.
Grbl 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 Grbl. If not, see <http://www.gnu.org/licenses/>.
*/
#include <string.h>
#ifdef ARDUINO
#include "../grbl/hal.h"
#include "../grbl/protocol.h"
#include "../grbl/nvs_buffer.h"
#include "../grbl/state_machine.h"
#else
#include "grbl/hal.h"
#include "grbl/protocol.h"
#include "grbl/settings.h"
#include "grbl/nvs_buffer.h"
#include "grbl/state_machine.h"
#endif
#include "modbus.h"
#define DEFAULT_BAUDRATE 3 // 19200
typedef struct queue_entry {
bool async;
bool sent;
modbus_message_t msg;
struct queue_entry *next;
} queue_entry_t;
static const uint32_t baud[] = { 2400, 4800, 9600, 19200, 38400, 115200 };
static const uint16_t silence[] = { 16, 8, 4, 2, 2, 2 };
static modbus_stream_t stream;
static uint16_t rx_timeout = 0, silence_until = 0, silence_timeout;
static int16_t exception_code = 0;
static queue_entry_t queue[MODBUS_QUEUE_LENGTH];
static modbus_settings_t modbus;
static volatile bool spin_lock = false, is_up = false;
static volatile queue_entry_t *tail, *head, *packet = NULL;
static volatile modbus_state_t state = ModBus_Idle;
static driver_reset_ptr driver_reset;
static on_execute_realtime_ptr on_execute_realtime;
static on_report_options_ptr on_report_options;
static nvs_address_t nvs_address;
static status_code_t modbus_set_baud (setting_id_t id, uint_fast16_t value);
static uint32_t modbus_get_baud (setting_id_t setting);
static void modbus_settings_restore (void);
static void modbus_settings_load (void);
// Compute the MODBUS RTU CRC
static uint16_t modbus_CRC16x (char *buf, uint_fast16_t len)
{
uint16_t crc = 0xFFFF;
uint_fast8_t pos, i;
for (pos = 0; pos < len; pos++) {
crc ^= (uint16_t)buf[pos]; // XOR byte into least sig. byte of crc
for (i = 8; i != 0; i--) { // Loop over each bit
if ((crc & 0x0001) != 0) { // If the LSB is set
crc >>= 1; // Shift right and XOR 0xA001
crc ^= 0xA001;
} else // Else LSB is not set
crc >>= 1; // Just shift right
}
}
// Note, this number has low and high bytes swapped, so use it accordingly (or swap bytes)
return crc;
}
/*
static bool valid_crc (char *buf, uint_fast16_t len)
{
uint16_t crc = modbus_CRC16x(buf, len - 2);
return buf[len - 1] == (crc >> 8) && buf[len - 2] == (crc & 0xFF);
}
*/
void modbus_poll (sys_state_t grbl_state)
{
static uint32_t last_ms;
UNUSED(grbl_state);
on_execute_realtime(grbl_state);
uint32_t ms = hal.get_elapsed_ticks();
if(ms == last_ms) // check once every ms
return;
spin_lock = true;
switch(state) {
case ModBus_Idle:
if(tail != head && !packet) {
packet = tail;
tail = tail->next;
state = ModBus_TX;
rx_timeout = modbus.rx_timeout;
if(stream.set_direction)
stream.set_direction(true);
packet->sent = true;
stream.flush_rx_buffer();
stream.write(((queue_entry_t *)packet)->msg.adu, ((queue_entry_t *)packet)->msg.tx_length);
}
break;
case ModBus_Silent:
if(ms >= silence_until) {
silence_until = 0;
state = ModBus_Idle;
}
break;
case ModBus_TX:
if(!stream.get_tx_buffer_count()) {
// When an auto-direction sense circuit supports higher baudrates is used at slower rates, it can switch during the off time (TXD is high) of some bit sequences.
// In some cases (teensy4.1) this can result in garbage characters in the RX buffer after a message is transmitted.
// Flushing the buffer prevents these characters from appearing as an RX message.
// Since Modbus is half-duplex, there should never be valid data recived during a message transmit.
stream.flush_rx_buffer();
state = ModBus_AwaitReply;
if(stream.set_direction)
stream.set_direction(false);
}
break;
case ModBus_AwaitReply:
if(rx_timeout && --rx_timeout == 0) {
if(packet->async)
state = ModBus_Silent;
else if(stream.read() == 1 && (stream.read() & 0x80)) {
exception_code = stream.read();
state = ModBus_Exception;
} else
state = ModBus_Timeout;
packet = NULL;
spin_lock = false;
if(state != ModBus_AwaitReply)
silence_until = ms + silence_timeout;
return;
}
if(stream.get_rx_buffer_count() >= packet->msg.rx_length) {
char *buf = ((queue_entry_t *)packet)->msg.adu;
do {
*buf++ = stream.read();
} while(--packet->msg.rx_length);
if((state = packet->async ? ModBus_Silent : ModBus_GotReply) == ModBus_Silent) {
stream.on_rx_packet(&((queue_entry_t *)packet)->msg);
packet = NULL;
}
silence_until = ms + silence_timeout;
}
break;
default:
break;
}
last_ms = ms;
spin_lock = false;
}
bool modbus_send (modbus_message_t *msg, bool block)
{
static queue_entry_t sync_msg = {0};
uint_fast16_t crc = modbus_CRC16x(msg->adu, msg->tx_length - 2);
msg->adu[msg->tx_length - 1] = crc >> 8;
msg->adu[msg->tx_length - 2] = crc & 0xFF;
while(spin_lock);
if(block) {
bool poll = true;
while(state != ModBus_Idle) {
grbl.on_execute_realtime(state_get());
if(ABORTED)
return false;
}
if(stream.set_direction)
stream.set_direction(true);
state = ModBus_TX;
rx_timeout = modbus.rx_timeout;
memcpy(&sync_msg.msg, msg, sizeof(modbus_message_t));
sync_msg.async = false;
stream.flush_rx_buffer();
stream.write(sync_msg.msg.adu, sync_msg.msg.tx_length);
packet = &sync_msg;
while(poll) {
grbl.on_execute_realtime(state_get());
if(ABORTED)
poll = false;
else switch(state) {
case ModBus_Timeout:
stream.on_rx_exception(0);
poll = false;
break;
case ModBus_Exception:
stream.on_rx_exception(exception_code == -1 ? 0 : (uint8_t)(exception_code & 0xFF));
poll = false;
break;
case ModBus_GotReply:
if(packet)
stream.on_rx_packet(&((queue_entry_t *)packet)->msg);
poll = block = false;
break;
default:
break;
}
}
packet = NULL;
state = silence_until > 0 ? ModBus_Silent : ModBus_Idle;
} else if(packet != &sync_msg) {
if(head->next != tail) {
head->async = true;
head->sent = false;
memcpy((void *)&(head->msg), msg, sizeof(modbus_message_t));
head = head->next;
}
}
return !block;
}
modbus_state_t modbus_get_state (void)
{
return state;
}
static void modbus_reset (void)
{
while(spin_lock);
packet = NULL;
tail = head;
silence_until = 0;
state = ModBus_Idle;
stream.flush_tx_buffer();
stream.flush_rx_buffer();
driver_reset();
}
static uint32_t get_baudrate (uint32_t rate)
{
uint32_t idx = sizeof(baud) / sizeof(uint32_t);
do {
if(baud[--idx] == rate)
return idx;
} while(idx);
return DEFAULT_BAUDRATE;
}
static const setting_group_detail_t modbus_groups [] = {
{ Group_Root, Group_ModBus, "ModBus"}
};
static const setting_detail_t modbus_settings[] = {
{ Settings_ModBus_BaudRate, Group_ModBus, "ModBus baud rate", NULL, Format_RadioButtons, "2400,4800,9600,19200,38400,115200", NULL, NULL, Setting_NonCoreFn, modbus_set_baud, modbus_get_baud, NULL },
{ Settings_ModBus_RXTimeout, Group_ModBus, "ModBus RX timeout", "milliseconds", Format_Integer, "####0", "50", "250", Setting_NonCore, &modbus.rx_timeout, NULL, NULL }
};
static void modbus_settings_save (void)
{
hal.nvs.memcpy_to_nvs(nvs_address, (uint8_t *)&modbus, sizeof(modbus_settings_t), true);
}
static setting_details_t details = {
.groups = modbus_groups,
.n_groups = sizeof(modbus_groups) / sizeof(setting_group_detail_t),
.settings = modbus_settings,
.n_settings = sizeof(modbus_settings) / sizeof(setting_detail_t),
.save = modbus_settings_save,
.load = modbus_settings_load,
.restore = modbus_settings_restore,
};
static setting_details_t *on_get_settings (void)
{
return &details;
}
static status_code_t modbus_set_baud (setting_id_t id, uint_fast16_t value)
{
modbus.baud_rate = baud[(uint32_t)value];
silence_timeout = silence[(uint32_t)value];
stream.set_baud_rate(modbus.baud_rate);
return Status_OK;
}
static uint32_t modbus_get_baud (setting_id_t setting)
{
return get_baudrate(modbus.baud_rate);
}
static void modbus_settings_restore (void)
{
modbus.rx_timeout = 50;
modbus.baud_rate = baud[DEFAULT_BAUDRATE];
hal.nvs.memcpy_to_nvs(nvs_address, (uint8_t *)&modbus, sizeof(modbus_settings_t), true);
}
static void modbus_settings_load (void)
{
if(hal.nvs.memcpy_from_nvs((uint8_t *)&modbus, nvs_address, sizeof(modbus_settings_t), true) != NVS_TransferResult_OK)
modbus_settings_restore();
is_up = true;
silence_timeout = silence[get_baudrate(modbus.baud_rate)];
stream.set_baud_rate(modbus.baud_rate);
}
static void onReportOptions (bool newopt)
{
on_report_options(newopt);
if(!newopt)
hal.stream.write("[PLUGIN:MODBUS v0.07]" ASCII_EOL);
}
bool modbus_isup (void)
{
return is_up;
}
static bool stream_is_valid (const io_stream_t *stream)
{
return !(stream->set_baud_rate == NULL ||
stream->get_tx_buffer_count == NULL ||
stream->get_rx_buffer_count == NULL ||
stream->write_n == NULL ||
stream->read == NULL ||
stream->reset_write_buffer == NULL ||
stream->reset_read_buffer == NULL ||
stream->set_enqueue_rt_handler == NULL);
}
static void pos_failed (uint_fast16_t state)
{
report_message("Modbus failed to initialize!", Message_Warning);
}
modbus_stream_t *modbus_init (const io_stream_t *io_stream, stream_set_direction_ptr set_direction)
{
if(stream_is_valid(io_stream) && (nvs_address = nvs_alloc(sizeof(modbus_settings_t)))) {
io_stream->set_enqueue_rt_handler(stream_buffer_all);
stream.set_baud_rate = io_stream->set_baud_rate;
stream.get_tx_buffer_count = io_stream->get_tx_buffer_count;
stream.get_rx_buffer_count = io_stream->get_rx_buffer_count;
stream.write = io_stream->write_n;
stream.read = io_stream->read;
stream.flush_tx_buffer = io_stream->reset_write_buffer;
stream.flush_rx_buffer = io_stream->reset_read_buffer;
stream.set_direction = set_direction;
driver_reset = hal.driver_reset;
hal.driver_reset = modbus_reset;
on_execute_realtime = grbl.on_execute_realtime;
grbl.on_execute_realtime = modbus_poll;
on_report_options = grbl.on_report_options;
grbl.on_report_options = onReportOptions;
details.on_get_settings = grbl.on_get_settings;
grbl.on_get_settings = on_get_settings;
head = tail = &queue[0];
uint_fast8_t idx;
for(idx = 0; idx < MODBUS_QUEUE_LENGTH; idx++)
queue[idx].next = idx == MODBUS_QUEUE_LENGTH - 1 ? &queue[0] : &queue[idx + 1];
} else {
protocol_enqueue_rt_command(pos_failed);
system_raise_alarm(Alarm_SelftestFailed);
}
return nvs_address != 0 ? &stream : NULL;
}