fix modbus slave wait before send option

Kconfig

@@ -104,6 +104,15 @@ menu "Modbus configuration"
         help
                 This option defines the number of data bits per ASCII character.
 
+    config FMB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS
+        int "Wait before send for ASCII communication mode (ms)"
+        default 0
+        range 0 1000
+        depends on FMB_COMM_MODE_ASCII_EN
+        help
+                This option defines timeout before slave sends the response in ASCII communication mode.
+                This allows to work with slow masters. Zero means delay before send is disabled.
+
     config FMB_SERIAL_ASCII_TIMEOUT_RESPOND_MS
         int "Response timeout for ASCII communication mode (ms)"
         default 1000

freemodbus/modbus/include/mbconfig.h

@@ -121,8 +121,10 @@ PR_BEGIN_EXTERN_C
  * transmitting the frame. If the master is to slow with enabling its
  * receiver then he will not receive the response correctly.
  */
-#ifndef MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS
+#ifndef CONFIG_FMB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS
 #define MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS    ( 0 )
+#else 
+#define MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS    ( CONFIG_FMB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS )
 #endif
 
 /*! \brief Maximum number of Modbus functions codes the protocol stack

freemodbus/port/porttimer.c

@@ -125,3 +125,8 @@ void vMBPortTimerClose(void)
     }
 #endif
 }
+
+void vMBPortTimersDelay(USHORT usTimeOutMS)
+{
+    vTaskDelay(usTimeOutMS / portTICK_PERIOD_MS);
+}