feat(modbus): disconnect and drop transactions on modbus timeout

Author: gsilvan

src/Inverter.cpp

@@ -21,10 +21,16 @@ bool Inverter::update() {
             this->_modbus.connect(this->ipAddress, this->port);
         } else {
             this->isConnected = true;
-            auto cb = [this](Modbus::ResultCode event, uint16_t transactionId, void* data) -> bool {
+            auto cb = [this](Modbus::ResultCode event, uint16_t transactionId, void *data) -> bool {
+                // Modified example:
+                // https://github.com/emelianov/modbus-esp8266/blob/master/examples/Callback/Transactional/Transactional.ino#L40-L48
                 if (event != Modbus::EX_SUCCESS) {
                     Serial.printf("Modbus error [%d]: %02X\n", transactionId, event);
                 }
+                if (event == Modbus::EX_TIMEOUT) {
+                    this->_modbus.disconnect(this->ipAddress);
+                    this->_modbus.dropTransactions();
+                }
                 return true;
             };
             this->_modbus.readHreg(this->ipAddress, 37004, (uint16_t *) &this->_batteryStateOfChargeRaw, 1, cb, this->modbusUnit);