From 72e2ec54331ebfbe0d0a1172792f87f7fccf1ea7 Mon Sep 17 00:00:00 2001
From: travis-farmer <travis.farmer@outlook.com>
Date: Sun, 1 Dec 2024 00:40:04 -0500
Subject: [PATCH] IO_Modbus: Trying to improve error recovery

---
 IO_Modbus.cpp | 21 ++++++++++++---------
 IO_Modbus.h   | 13 ++++++++-----
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/IO_Modbus.cpp b/IO_Modbus.cpp
index d1fd185..c13658b 100644
--- a/IO_Modbus.cpp
+++ b/IO_Modbus.cpp
@@ -222,10 +222,11 @@ void ModbusRTUComm::setTimeout(unsigned long timeout) {
 ModbusRTUCommError ModbusRTUComm::readAdu(ModbusADU& adu) {
   adu.setRtuLen(0);
   unsigned long startMillis = millis();
+  if (_startTimeout == 0UL) _startTimeout = startMillis;
   if (!_serial.available()) {
     //if (millis() - startMillis >= _readTimeout) return MODBUS_RTU_COMM_TIMEOUT;
     _waiting_for_read = true;
-    if (millis() - startMillis >= _readTimeout) {
+    if (millis() - _startTimeout >= _readTimeout) {
       //_serial.flush();
       return MODBUS_RTU_COMM_TIMEOUT;
     } else {
@@ -234,6 +235,7 @@ ModbusRTUCommError ModbusRTUComm::readAdu(ModbusADU& adu) {
     
   }
   _waiting_for_read = false;
+  _startTimeout = 0UL;
   uint16_t len = 0;
   unsigned long startMicros = micros();
   do {
@@ -493,14 +495,15 @@ ModbusRTUMasterError Modbus::_translateCommError(ModbusRTUCommError commError) {
 
 
 // Constructor for Modbus
-Modbus::Modbus(uint8_t busNo, HardwareSerial &serial, unsigned long baud, uint16_t cycleTimeMS, int8_t txPin) : _rtuComm(serial, txPin) {
+Modbus::Modbus(uint8_t busNo, HardwareSerial &serial, unsigned long baud, uint16_t cycleTimeMS, int8_t txPin, int waitA, int waitB) : _rtuComm(serial, txPin) {
   _baud = baud;
   _serialD = &serial;
   _txPin = txPin;
   _rtuComm.setTimeout(500);
   _busNo = busNo;
   _cycleTime = cycleTimeMS * 1000UL; // convert from milliseconds to microseconds.
-  
+  _waitA = waitA;
+  _waitB = waitB;
   // Add device to HAL device chain
   IODevice::addDevice(this);
   
@@ -555,14 +558,14 @@ void Modbus::_loop(unsigned long currentMicros) {
       break;
   }
   if (error == MODBUS_RTU_MASTER_WAITING) {
-    if (_waitCounter > 10) { // retry after 10 cycles of waiting.
-      _resetWaiting();
+    if (_waitCounter > _waitA) { // retry after 10 cycles of waiting, or user setting waitA.
+      _resetWaiting(); // reset Waiting flag so it retries.
       _waitCounter = 0;
       _waitCounterB++;
     } else {
       _waitCounter++;
     }
-    if (_waitCounterB > 10) { // move on to next node if fails 10 times.
+    if (_waitCounterB > _waitB) { // move on to next node if fails 10 times, or user setting waitB.
       _waitCounter = 0;
       _waitCounterB = 0;
       _operationCount = 0;
@@ -573,9 +576,9 @@ void Modbus::_loop(unsigned long currentMicros) {
     _waitCounterB = 0;
   }
   
-  if (error != MODBUS_RTU_MASTER_WAITING) {
-    if (_operationCount < 3) {
-      _operationCount++;
+  if (error == MODBUS_RTU_MASTER_SUCCESS) { // should have the effect of retrying same opperation until success
+    if (_operationCount < 3) { //              unless it fails waitB and moves on to next node. may even
+      _operationCount++; //                    improve error recovery...
     } else {
       _operationCount = 0;
       _currentNode = _currentNode->getNext();
diff --git a/IO_Modbus.h b/IO_Modbus.h
index 5b08f5c..1a42c16 100644
--- a/IO_Modbus.h
+++ b/IO_Modbus.h
@@ -122,8 +122,9 @@ class ModbusRTUComm {
     
     unsigned long _charTimeout;
     unsigned long _frameTimeout;
-    unsigned long _postDelay = 0;
-    unsigned long _readTimeout = 0;
+    unsigned long _postDelay = 0UL;
+    unsigned long _readTimeout = 0UL;
+    unsigned long _startTimeout = 0UL;
 };
 
 enum ModbusRTUMasterError : uint8_t {
@@ -317,13 +318,15 @@ private:
   ModbusRTUMasterError _writeSingleValue(uint8_t id, uint8_t functionCode, uint16_t address, uint16_t value);
   int _waitCounter = 0;
   int _waitCounterB = 0;
+  int _waitA;
+  int _waitB;
 
   void _resetWaiting() {
     _rtuComm._waiting_for_read = false;
   }
 public:
-  static void create(uint8_t busNo, HardwareSerial& serial, unsigned long baud, uint16_t cycleTimeMS=500, int8_t txPin=-1) {
-    new Modbus(busNo, serial, baud, cycleTimeMS, txPin);
+  static void create(uint8_t busNo, HardwareSerial& serial, unsigned long baud, uint16_t cycleTimeMS=500, int8_t txPin=-1, int waitA=10, int waitB=10) {
+    new Modbus(busNo, serial, baud, cycleTimeMS, txPin, waitA, waitB);
   }
   HardwareSerial *_serialD;
   ModbusRTUComm _rtuComm;
@@ -388,7 +391,7 @@ public:
   }
 
 protected:
-  Modbus(uint8_t busNo, HardwareSerial &serial, unsigned long baud, uint16_t cycleTimeMS, int8_t txPin);
+  Modbus(uint8_t busNo, HardwareSerial &serial, unsigned long baud, uint16_t cycleTimeMS, int8_t txPin, int waitA, int waitB);
 
 public: