My English is poor?? so the description may not be clear enough. The modbus tcp with lwip in STM32F4??always show timeout, when communication with modbus poll. And the case is: (1)the version of lwip is 1.3.2 (2)#defien TCP_TMR_INTERVAL 10 (3)no system, #define NO_SYS 1 (4)#define MEM_ALIGNMENT 4 (5)#define MEM_SIZE (12*1024) (6)#define MEMP_NUM_PBUF 10 (7)#define MEMP_NUM_UDP_PCB 5 (8)#define MEMP_NUM_TCP_PCB 2 (9)#define MEMP_NUM_TCP_PCB_LISTEN 2 (10)#define MEMP_NUM_TCP_SEG 20 (11)#define MEMP_NUM_SYS_TIMEOUT 3 (12)#define PBUF_POOL_SIZE 10 (13)#define PBUF_POOL_BUFSIZE 1600 (14)#define LWIP_TCP 1 (15)#define TCP_TTL 255 (16)#define TCP_QUEUE_OOSEQ 0 (17)#define TCP_MSS (1500 - 40) (18)#define TCP_SND_BUF (8*TCP_MSS) (19)#define TCP_SND_QUEUELEN (4* TCP_SND_BUF/TCP_MSS) (20)#define TCP_WND (4*TCP_MSS) (21)#define LWIP_ICMP 1 (22)#define LWIP_DHCP 1 (23)#define LWIP_UDP 1 (24)#define UDP_TTL 255 (25)#define LWIP_STATS 0 (26)#define LWIP_PROVIDE_ERRNO 1 (27)#define LWIP_NETCONN 0 (28)#define LWIP_SOCKET 0
I have changed the value of these parameters, but it seems unuseful. I want to know what is the reason for timeout. It is inappropriate configurations, or something else? I am confused, please help me.