modbus: add a serial RTU backend.

[libsigrok.git] / src / modbus / modbus.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2015 Aurelien Jacobs <aurel@gnuage.org>
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include "libsigrok.h"
#include "libsigrok-internal.h"

#include <glib.h>
#include <string.h>

#define LOG_PREFIX "modbus"

SR_PRIV extern const struct sr_modbus_dev_inst modbus_serial_rtu_dev;

static const struct sr_modbus_dev_inst *modbus_devs[] = {
#ifdef HAVE_LIBSERIALPORT
	&modbus_serial_rtu_dev,  /* must be last as it matches any resource */
#endif
};

static struct sr_dev_inst *sr_modbus_scan_resource(const char *resource,
		const char *serialcomm, int modbusaddr,
		struct sr_dev_inst *(*probe_device)(struct sr_modbus_dev_inst *modbus))
{
	struct sr_modbus_dev_inst *modbus;
	struct sr_dev_inst *sdi;

	if (!(modbus = modbus_dev_inst_new(resource, serialcomm, modbusaddr)))
		return NULL;

	if (sr_modbus_open(modbus) != SR_OK) {
		sr_info("Couldn't open MODBUS device.");
		sr_modbus_free(modbus);
		return NULL;
	};

	if ((sdi = probe_device(modbus)))
		return sdi;

	sr_modbus_close(modbus);
	sr_modbus_free(modbus);
	return NULL;
}

/**
 *  Scan for MODBUS devices which match a probing function.
 *
 *  @param drvc the driver context doing the scan.
 *  @param options the scan options to find devies.
 *  @param probe_device the callback function that will be called for each
 *                      found devices to validate wheter this device matches
 *                      what we are scanning for.
 *
 *  @return a list of the devices found or NULL if no device found.
 */
SR_PRIV GSList *sr_modbus_scan(struct drv_context *drvc, GSList *options,
		struct sr_dev_inst *(*probe_device)(struct sr_modbus_dev_inst *modbus))
{
	GSList *resources, *l, *devices;
	struct sr_dev_inst *sdi;
	const char *resource = NULL;
	const char *serialcomm = NULL;
	int modbusaddr = 1;
	gchar **res;
	unsigned i;

	for (l = options; l; l = l->next) {
		struct sr_config *src = l->data;
		switch (src->key) {
		case SR_CONF_CONN:
			resource = g_variant_get_string(src->data, NULL);
			break;
		case SR_CONF_SERIALCOMM:
			serialcomm = g_variant_get_string(src->data, NULL);
			break;
		case SR_CONF_MODBUSADDR:
			modbusaddr = g_variant_get_uint64(src->data);
			break;
		}
	}

	devices = NULL;
	for (i = 0; i < ARRAY_SIZE(modbus_devs); i++) {
		if ((resource && strcmp(resource, modbus_devs[i]->prefix))
		    || !modbus_devs[i]->scan)
			continue;
		resources = modbus_devs[i]->scan(modbusaddr);
		for (l = resources; l; l = l->next) {
			res = g_strsplit(l->data, ":", 2);
			if (res[0] && (sdi = sr_modbus_scan_resource(res[0],
			                                 serialcomm ? serialcomm : res[1],
			                                 modbusaddr, probe_device))) {
				devices = g_slist_append(devices, sdi);
				sdi->connection_id = g_strdup(l->data);
			}
			g_strfreev(res);
		}
		g_slist_free_full(resources, g_free);
	}

	if (!devices && resource) {
		sdi = sr_modbus_scan_resource(resource, serialcomm, modbusaddr,
		                              probe_device);
		if (sdi)
			devices = g_slist_append(NULL, sdi);
	}

	/* Tack a copy of the newly found devices onto the driver list. */
	if (devices)
		drvc->instances = g_slist_concat(drvc->instances, g_slist_copy(devices));

	return devices;
}

/**
 *  Allocate and initialize struct for a MODBUS device instance.
 *
 *  @param resource the resource description string.
 *  @param serialcomm additionnal parameters for serial port resources.
 *
 *  @return the allocated sr_modbus_dev_inst structure or NULL on failure.
 */
SR_PRIV struct sr_modbus_dev_inst *modbus_dev_inst_new(const char *resource,
		const char *serialcomm, int modbusaddr)
{
	struct sr_modbus_dev_inst *modbus = NULL;
	const struct sr_modbus_dev_inst *modbus_dev;
	gchar **params;
	unsigned i;

	for (i = 0; i < ARRAY_SIZE(modbus_devs); i++) {
		modbus_dev = modbus_devs[i];
		if (!strncmp(resource, modbus_dev->prefix, strlen(modbus_dev->prefix))) {
			sr_dbg("Opening %s device %s.", modbus_dev->name, resource);
			modbus = g_malloc(sizeof(*modbus));
			*modbus = *modbus_dev;
			modbus->priv = g_malloc0(modbus->priv_size);
			modbus->read_timeout_ms = 1000;
			params = g_strsplit(resource, "/", 0);
			if (modbus->dev_inst_new(modbus->priv, resource,
			                         params, serialcomm, modbusaddr) != SR_OK) {
				sr_modbus_free(modbus);
				modbus = NULL;
			}
			g_strfreev(params);
			break;
		}
	}

	return modbus;
}

/**
 * Open MODBUS device.
 *
 * @param modbus Previously initialized MODBUS device structure.
 *
 * @return SR_OK on success, SR_ERR on failure.
 */
SR_PRIV int sr_modbus_open(struct sr_modbus_dev_inst *modbus)
{
	return modbus->open(modbus->priv);
}

/**
 * Add an event source for an MODBUS device.
 *
 * @param session The session to add the event source to.
 * @param modbus Previously initialized MODBUS device structure.
 * @param events Events to check for.
 * @param timeout Max time to wait before the callback is called, ignored if 0.
 * @param cb Callback function to add. Must not be NULL.
 * @param cb_data Data for the callback function. Can be NULL.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or
 *         SR_ERR_MALLOC upon memory allocation errors.
 */
SR_PRIV int sr_modbus_source_add(struct sr_session *session,
		struct sr_modbus_dev_inst *modbus, int events, int timeout,
		sr_receive_data_callback cb, void *cb_data)
{
	return modbus->source_add(session, modbus->priv, events, timeout, cb, cb_data);
}

/**
 * Remove event source for an MODBUS device.
 *
 * @param session The session to remove the event source from.
 * @param modbus Previously initialized MODBUS device structure.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or
 *         SR_ERR_MALLOC upon memory allocation errors, SR_ERR_BUG upon
 *         internal errors.
 */
SR_PRIV int sr_modbus_source_remove(struct sr_session *session,
		struct sr_modbus_dev_inst *modbus)
{
	return modbus->source_remove(session, modbus->priv);
}

/**
 * Send a MODBUS command.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param request buffer containing the MODBUS command to send.
 * @param request_size the size of the request buffer.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or
 *         SR_ERR on failure.
 */
SR_PRIV int sr_modbus_request(struct sr_modbus_dev_inst *modbus,
		uint8_t *request, int request_size)
{
	if (!request || request_size < 1)
		return SR_ERR_ARG;

	return modbus->send(modbus->priv, request, request_size);
}

/**
 * Receive a MODBUS reply.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param reply buffer to store the received MODBUS reply.
 * @param reply_size the size of the reply buffer.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or
 *         SR_ERR on failure.
 */
SR_PRIV int sr_modbus_reply(struct sr_modbus_dev_inst *modbus,
		uint8_t *reply, int reply_size)
{
	int len, ret;
	gint64 laststart;
	unsigned int elapsed_ms;

	if (!reply || reply_size < 2)
		return SR_ERR_ARG;

	laststart = g_get_monotonic_time();

	ret = modbus->read_begin(modbus->priv, reply);
	if (ret != SR_OK)
		return ret;
	if (*reply & 0x80)
		reply_size = 2;

	reply++;
	reply_size--;

	while (reply_size > 0) {
		len = modbus->read_data(modbus->priv, reply, reply_size);
		if (len < 0) {
			sr_err("Incompletely read MODBUS response.");
			return SR_ERR;
		} else if (len > 0) {
			laststart = g_get_monotonic_time();
		}
		reply += len;
		reply_size -= len;
		elapsed_ms = (g_get_monotonic_time() - laststart) / 1000;
		if (elapsed_ms >= modbus->read_timeout_ms) {
			sr_err("Timed out waiting for MODBUS response.");
			return SR_ERR;
		}
	}

	ret = modbus->read_end(modbus->priv);
	if (ret != SR_OK)
		return ret;

	return SR_OK;
}

/**
 * Send a MODBUS command and receive the corresponding reply.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param request buffer containing the MODBUS command to send.
 * @param request_size the size of the request buffer.
 * @param reply buffer to store the received MODBUS reply.
 * @param reply_size the size of the reply buffer.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or
 *         SR_ERR on failure.
 */
SR_PRIV int sr_modbus_request_reply(struct sr_modbus_dev_inst *modbus,
		uint8_t *request, int request_size, uint8_t *reply, int reply_size)
{
	int ret;
	ret = sr_modbus_request(modbus, request, request_size);
	if (ret != SR_OK)
		return ret;
	return sr_modbus_reply(modbus, reply, reply_size);
}

enum {
	MODBUS_READ_COILS               = 0x01,
	MODBUS_READ_HOLDING_REGISTERS   = 0x03,
	MODBUS_WRITE_COIL               = 0x05,
	MODBUS_WRITE_MULTIPLE_REGISTERS = 0x10,
};

static int sr_modbus_error_check(const uint8_t *reply)
{
	const char *function = "UNKNOWN";
	const char *error = NULL;
	char buf[8];

	if (!(reply[0] & 0x80))
		return FALSE;

	switch (reply[0] & ~0x80) {
	case MODBUS_READ_COILS:
		function = "MODBUS_READ_COILS";  break;
	case MODBUS_READ_HOLDING_REGISTERS:
		function = "READ_HOLDING_REGISTERS";  break;
	case MODBUS_WRITE_COIL:
		function = "WRITE_COIL"; break;
	case MODBUS_WRITE_MULTIPLE_REGISTERS:
		function = "WRITE_MULTIPLE_REGISTERS"; break;
	}

	switch (reply[1]) {
	case 0x01:
		error = "ILLEGAL FUNCTION";  break;
	case 0x02:
		error = "ILLEGAL DATA ADDRESS";  break;
	case 0x03:
		error = "ILLEGAL DATA VALUE"; break;
	case 0x04:
		error = "SLAVE DEVICE FAILURE"; break;
	case 0x05:
		error = "ACKNOWLEDGE"; break;
	case 0x06:
		error = "SLAVE DEVICE BUSY"; break;
	case 0x08:
		error = "MEMORY PARITY ERROR"; break;
	case 0x0A:
		error = "GATEWAY PATH UNAVAILABLE"; break;
	case 0x0B:
		error = "GATEWAY TARGET DEVICE FAILED TO RESPOND"; break;
	}
	if (!error) {
		snprintf(buf, sizeof(buf), "0x%X", reply[1]);
		error = buf;
	}

	sr_err("%s error executing %s function.", error, function);
	return TRUE;
}

/**
 * Send a MODBUS read coils command and receive the corresponding coils values.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param address the MODBUS address of the first coil to read,
 *                or -1 to read the reply of a previouly sent
 *                read coils command.
 * @param nb_coils the number of coils to read.
 * @param coils buffer to store all the received coils values (1 bit per coil),
 *              or NULL to send the read coil command without reading the reply.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments,
 *         SR_ERR_DATA upon invalid data, or SR_ERR on failure.
 */
SR_PRIV int sr_modbus_read_coils(struct sr_modbus_dev_inst *modbus,
		int address, int nb_coils, uint8_t *coils)
{
	uint8_t request[5], reply[2 + (nb_coils + 7) / 8];
	int ret;

	if (address < -1 || address > 0xFFFF || nb_coils < 1 || nb_coils > 2000)
		return SR_ERR_ARG;

	W8  (request+0, MODBUS_READ_COILS);
	WB16(request+1, address);
	WB16(request+3, nb_coils);

	if (address >= 0) {
		ret = sr_modbus_request(modbus, request, sizeof(request));
		if (ret != SR_OK)
			return ret;
	}

	if (coils) {
		ret = sr_modbus_reply(modbus, reply, sizeof(reply));
		if (ret != SR_OK)
			return ret;
		if (sr_modbus_error_check(reply))
			return SR_ERR_DATA;
		if (reply[0] != request[0] || R8(reply+1) != (uint8_t)((nb_coils+7)/8))
			return SR_ERR_DATA;
		memcpy(coils, reply+2, (nb_coils+7)/8);
	}

	return SR_OK;
}

/**
 * Send a MODBUS read holding registers command and receive the corresponding
 * registers values.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param address the MODBUS address of the first register to read,
 *                or -1 to read the reply of a previouly sent
 *                read registers command.
 * @param nb_registers the number of registers to read.
 * @param registers buffer to store all the received registers values,
 *                  or NULL to send the read holding registers command
 *                  without reading the reply.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments,
 *         SR_ERR_DATA upon invalid data, or SR_ERR on failure.
 */
SR_PRIV int sr_modbus_read_holding_registers(struct sr_modbus_dev_inst *modbus,
		int address, int nb_registers, uint16_t *registers)
{
	uint8_t request[5], reply[2 + 2*nb_registers];
	int ret;

	if (address < -1 || address > 0xFFFF
	    || nb_registers < 1 || nb_registers > 125)
		return SR_ERR_ARG;

	W8  (request+0, MODBUS_READ_HOLDING_REGISTERS);
	WB16(request+1, address);
	WB16(request+3, nb_registers);

	if (address >= 0) {
		ret = sr_modbus_request(modbus, request, sizeof(request));
		if (ret != SR_OK)
			return ret;
	}

	if (registers) {
		ret = sr_modbus_reply(modbus, reply, sizeof(reply));
		if (ret != SR_OK)
			return ret;
		if (sr_modbus_error_check(reply))
			return SR_ERR_DATA;
		if (reply[0] != request[0] || R8(reply+1) != (uint8_t)(2*nb_registers))
			return SR_ERR_DATA;
		memcpy(registers, reply+2, 2*nb_registers);
	}

	return SR_OK;
}

/**
 * Send a MODBUS write coil command.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param address the MODBUS address of the coil to write.
 * @param value the new value to assign to this coil.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments,
 *         SR_ERR_DATA upon invalid data, or SR_ERR on failure.
 */
SR_PRIV int sr_modbus_write_coil(struct sr_modbus_dev_inst *modbus,
		int address, int value)
{
	uint8_t request[5], reply[5];
	int ret;

	if (address < 0 || address > 0xFFFF)
		return SR_ERR_ARG;

	W8  (request+0, MODBUS_WRITE_COIL);
	WB16(request+1, address);
	WB16(request+3, value ? 0xFF00 : 0);

	ret = sr_modbus_request_reply(modbus, request, sizeof(request),
	                                      reply  , sizeof(reply));
	if (ret != SR_OK)
		return ret;
	if (sr_modbus_error_check(reply))
		return SR_ERR_DATA;
	if (memcmp(request, reply, sizeof(reply)))
		return SR_ERR_DATA;
	return SR_OK;
}

/**
 * Send a MODBUS write multiple registers command.
 *
 * @param modbus Previously initialized MODBUS device structure.
 * @param address the MODBUS address of the first register to write.
 * @param nb_registers the number of registers to write.
 * @param registers buffer holding all the registers values to write.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments,
 *         SR_ERR_DATA upon invalid data, or SR_ERR on failure.
 */
SR_PRIV int sr_modbus_write_multiple_registers(struct sr_modbus_dev_inst*modbus,
		int address, int nb_registers, uint16_t *registers)
{
	uint8_t request[6+2*nb_registers], reply[5];
	int ret;

	if (address < 0 || address > 0xFFFF
	    || nb_registers < 1 || nb_registers > 123 || !registers)
		return SR_ERR_ARG;

	W8  (request+0, MODBUS_WRITE_MULTIPLE_REGISTERS);
	WB16(request+1, address);
	WB16(request+3, nb_registers);
	W8  (request+5, 2*nb_registers);
	memcpy(request+6, registers, 2*nb_registers);

	ret = sr_modbus_request_reply(modbus, request, sizeof(request),
	                                      reply  , sizeof(reply));
	if (ret != SR_OK)
		return ret;
	if (sr_modbus_error_check(reply))
		return SR_ERR_DATA;
	if (memcmp(request, reply, sizeof(reply)))
		return SR_ERR_DATA;
	return SR_OK;
}

/**
 * Close MODBUS device.
 *
 * @param modbus Previously initialized MODBUS device structure.
 *
 * @return SR_OK on success, SR_ERR on failure.
 */
SR_PRIV int sr_modbus_close(struct sr_modbus_dev_inst *modbus)
{
	return modbus->close(modbus->priv);
}

/**
 * Free MODBUS device.
 *
 * @param modbus Previously initialized MODBUS device structure.
 *
 * @return SR_OK on success, SR_ERR on failure.
 */
SR_PRIV void sr_modbus_free(struct sr_modbus_dev_inst *modbus)
{
	modbus->free(modbus->priv);
	g_free(modbus->priv);
	g_free(modbus);
}