ESP32 Forum

Hardware:
Board: ESP32-S3 Dev Module
Ethernet: W5500 SPI Ethernet Modul

Description:
Hello, I am trying to make solution with one Master and more then 5 Slaves, for example 20. I read thet the Modbus implementation von ESP connected to all slaves at the beginning and then starting a modbus communication. Becose of low number of sockets, it is recommendet to connect not more then 5 slaves.
My decision is to connect slave number 1 then disconnect and go to slave N2 and so own. Based on example from Espressif:

To connect i use:
______________________________________________________________________________________________________________
void mb_master_start_dm()
{
vTaskDelay(100);
mb_tcp_addr_type_t ip_addr_type;

ip_addr_type = MB_IPV4;

int ip_cnt = master_get_slave_ip_stdin(slave_ip_address_table);
if (ip_cnt) { ESP_LOGI(TAG, "Configured %d IP addresse(s).", ip_cnt); }
else
{
ESP_LOGE(TAG, "Fail to get IP address from stdin. Continue.");
// return ESP_ERR_NOT_FOUND;
}

mb_communication_info_t comm_info = { 0 };
comm_info.ip_port = MB_TCP_PORT;
comm_info.ip_addr_type = ip_addr_type;
comm_info.ip_mode = MB_MODE_TCP;
comm_info.ip_addr = (void *)slave_ip_address_table;

volatile esp_netif_t *pp_netif = NULL;
ntwrk_get_active_netif(&pp_netif);
comm_info.ip_netif_ptr = pp_netif; //(void*)get_example_netif();

ESP_ERROR_CHECK(master_init_mb_master_dm(&comm_info));
vTaskDelay(50);

}
______________________________________________________________________________________________________________
and
______________________________________________________________________________________________________________
static esp_err_t master_init_mb_master_dm(mb_communication_info_t *comm_info)
{
void *master_handler = NULL;

esp_err_t err = mbc_master_init_tcp(&master_handler);
MB_RETURN_ON_FALSE((master_handler != NULL), ESP_ERR_INVALID_STATE, TAG, "mb controller initialization fail.");
MB_RETURN_ON_FALSE((err == ESP_OK), ESP_ERR_INVALID_STATE, TAG, "mb controller initialization fail, returns(0x%lx).", (uint32_t)err);

err = mbc_master_setup((void *)comm_info);
MB_RETURN_ON_FALSE((err == ESP_OK), ESP_ERR_INVALID_STATE, TAG, "mb controller setup fail, returns(0x%lx).", (uint32_t)err);

err = mbc_master_set_descriptor(&device_parameters, num_device_parameters);
MB_RETURN_ON_FALSE((err == ESP_OK), ESP_ERR_INVALID_STATE, TAG, "mb controller set descriptor fail, returns(0x%lx).", (uint32_t)err);
ESP_LOGI(TAG, "Modbus master stack initialized...");

err = mbc_master_start();
MB_RETURN_ON_FALSE((err == ESP_OK), ESP_ERR_INVALID_STATE, TAG, "mb controller start fail, returns(0x%lx).", (uint32_t)err);
vTaskDelay(5);
return err;
}
______________________________________________________________________________________________________________

For disconnect i call:
______________________________________________________________________________________________________________
static esp_err_t master_destroy(void)
{
esp_err_t err = mbc_master_destroy();
MB_RETURN_ON_FALSE((err == ESP_OK), ESP_ERR_INVALID_STATE, TAG, "mbc_master_destroy fail, returns(0x%lx).", (uint32_t)err);
ESP_LOGI(TAG, "Modbus master stack destroy...");
return err;
}
______________________________________________________________________________________________________________


i fixed a problem with sockets that would be not removed.

after some successful connects, communications and disconnects i am getting a core panic:

I (724264) MB_TCP_MASTER_PORT: Connecting to slaves...
-I (724264) MB_TCP_MASTER_PORT: Connected 1 slaves, start polling...
Guru Meditation Error: Core 0 panic'ed (Interrupt wdt timeout on CPU0).

Core 0 register dump:
PC : 0x4037cb38 PS : 0x00060234 A0 : 0x80382e78 A1 : 0x3fcd4620
0x4037cb38: esp_cpu_compare_and_set at C:/Users/Mykyta/esp_n/esp-idf/components/esp_hw_support/cpu.c:406


Has someone a solution to this problem?

Hello!
I have the same problem, have you made any progress?
thank you!

Similar problem on my end as well.

My application involves reconfiguring the Wifi and restart the the Modbus TCP Slave init() when the correct IP address is acquired.
I am trying to use mbc_slave_destroy() to stop the slave and it seems it doesn't like reconfiguring the TCP info again.

Update (25 September 2024): If this is useful to anyone, the github component for modbus highlights the changes made to the library for closing the Modbus TCP peripheral.
Link: https://github.com/espressif/esp-modbus ... a825afad0a