From bb25134b6c9a781a73ba376dde7c15b8a221f41b Mon Sep 17 00:00:00 2001
From: Eduard Iten <eduard@iten.pro>
Date: Thu, 3 Jul 2025 18:59:01 +0200
Subject: [PATCH] feat(modbus): Implement persistent and improved
 reconfiguration for Modbus server

This commit enhances the Modbus server's configuration handling by:

- Loading saved baudrate and unit ID settings during initialization, ensuring persistence across reboots.
- Providing improved feedback during `modbus_reconfigure`, including logging for successful changes and informing the user when a device restart is required for changes to take effect.
- Saving new configuration settings even if immediate reinitialization fails, allowing them to be applied on the next boot.
---
 software/lib/modbus_server/modbus_server.c | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/software/lib/modbus_server/modbus_server.c b/software/lib/modbus_server/modbus_server.c
index 9175b63..1d78f77 100644
--- a/software/lib/modbus_server/modbus_server.c
+++ b/software/lib/modbus_server/modbus_server.c
@@ -158,6 +158,17 @@ static struct modbus_user_callbacks mbs_cbs = {
 int modbus_server_init(void)
 {
 	k_timer_init(&watchdog_timer, watchdog_timer_handler, NULL);
+	
+	// Load saved settings
+	uint32_t saved_baudrate = 19200;
+	uint8_t saved_unit_id = 1;
+	settings_load_one("modbus/baudrate", &saved_baudrate, sizeof(saved_baudrate));
+	settings_load_one("modbus/unit_id", &saved_unit_id, sizeof(saved_unit_id));
+	
+	// Apply loaded settings
+	server_param.serial.baud = saved_baudrate;
+	server_param.server.unit_id = saved_unit_id;
+	
 	const char iface_name[] = {DEVICE_DT_NAME(MODBUS_NODE)};
 #if DT_NODE_HAS_COMPAT(DT_PARENT(MODBUS_NODE), zephyr_cdc_acm_uart)
 	const struct device *const dev = DEVICE_DT_GET(DT_PARENT(MODBUS_NODE));
@@ -182,20 +193,37 @@ int modbus_server_init(void)
 		return modbus_iface;
 	}
 	server_param.server.user_cb = &mbs_cbs;
+	
+	LOG_INF("Starting Modbus server: baudrate=%u, unit_id=%u", saved_baudrate, saved_unit_id);
 	return modbus_init_server(modbus_iface, server_param);
 }
 
 int modbus_reconfigure(uint32_t baudrate, uint8_t unit_id)
 {
+	// Update parameters
 	server_param.serial.baud = baudrate;
 	server_param.server.unit_id = unit_id;
 
+	// Try to reinitialize - this should work for most cases
 	int ret = modbus_init_server(modbus_iface, server_param);
 
 	if (ret == 0)
 	{
 		settings_save_one("modbus/baudrate", &baudrate, sizeof(baudrate));
 		settings_save_one("modbus/unit_id", &unit_id, sizeof(unit_id));
+		LOG_INF("Modbus reconfigured: baudrate=%u, unit_id=%u", baudrate, unit_id);
+	}
+	else
+	{
+		LOG_ERR("Failed to reconfigure Modbus: %d", ret);
+		LOG_INF("Modbus reconfiguration requires restart to take effect");
+		
+		// Save settings for next boot
+		settings_save_one("modbus/baudrate", &baudrate, sizeof(baudrate));
+		settings_save_one("modbus/unit_id", &unit_id, sizeof(unit_id));
+		
+		LOG_INF("Settings saved. Type 'reset' to restart the device and apply the change.");
+		return 0; // Return success since settings are saved
 	}
 
 	return ret;