From 7b291d87a9ce24833f26ad6192eea6dc4b6251f7 Mon Sep 17 00:00:00 2001
From: 19y <maxicon@qq.com>
Date: Mon, 29 Sep 2025 20:34:21 +0800
Subject: [PATCH] Fix: Fixed a reading bug in MODBUS-RTU when using DMA

---
 examples/stm32/nmbs/port.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/examples/stm32/nmbs/port.c b/examples/stm32/nmbs/port.c
index f7cf225..8271f57 100644
--- a/examples/stm32/nmbs/port.c
+++ b/examples/stm32/nmbs/port.c
@@ -195,6 +195,11 @@ int32_t write_socket(const uint8_t* buf, uint16_t count, int32_t byte_timeout_ms
 #ifdef NMBS_RTU
 static int32_t read_serial(uint8_t* buf, uint16_t count, int32_t byte_timeout_ms, void* arg) {
 #if MB_UART_DMA
+    if(byte_timeout_ms==0)
+    {
+        xQueueReset(rtu_rx_q);
+        return 0;
+    }
     uint32_t tick_start = HAL_GetTick();
     while (uxQueueMessagesWaiting(rtu_rx_q) < count) {
         if (HAL_GetTick() - tick_start >= (uint32_t) byte_timeout_ms) {