diff --git a/IO_Modbus.cpp b/IO_Modbus.cpp
index 74929f9..4e9da46 100644
--- a/IO_Modbus.cpp
+++ b/IO_Modbus.cpp
@@ -538,23 +538,23 @@ void Modbus::_loop(unsigned long currentMicros) {
   switch (_operationCount) {
     case 0:
       error = writeMultipleHoldingRegisters(_currentNode->getNodeID(), 0, (uint16_t*) _currentNode->holdingRegisters, _currentNode->getNumHoldingRegisters());
-      if (error != 0 && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusHR: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumHoldingRegisters(), errorStrings[error]);
-      if (error != 0 && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
+      if (error != MODBUS_RTU_MASTER_SUCCESS && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusHR: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumHoldingRegisters(), errorStrings[error]);
+      if (error != MODBUS_RTU_MASTER_SUCCESS && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
       break;
     case 1:
       error = writeMultipleCoils(_currentNode->getNodeID(), 0, (int*) _currentNode->coils, _currentNode->getNumCoils());
-      if (error != 0 && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusMC: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumCoils(), errorStrings[error]);
-      if (error != 0 && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
+      if (error != MODBUS_RTU_MASTER_SUCCESS && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusMC: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumCoils(), errorStrings[error]);
+      if (error != MODBUS_RTU_MASTER_SUCCESS && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
       break;
     case 2:
       error = readDiscreteInputs(_currentNode->getNodeID(), 0, (int*) _currentNode->discreteInputs, _currentNode->getNumDiscreteInputs());
-      if (error != 0 && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusDI: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumDiscreteInputs(), errorStrings[error]);
-      if (error != 0 && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
+      if (error != MODBUS_RTU_MASTER_SUCCESS && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusDI: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumDiscreteInputs(), errorStrings[error]);
+      if (error != MODBUS_RTU_MASTER_SUCCESS && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
       break;
     case 3:
       error = readInputRegisters(_currentNode->getNodeID(), 0, (uint16_t*) _currentNode->inputRegisters, _currentNode->getNumInputRegisters());
-      if (error != 0 && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusIR: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumInputRegisters(), errorStrings[error]);
-      if (error != 0 && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
+      if (error != MODBUS_RTU_MASTER_SUCCESS && error != MODBUS_RTU_MASTER_WAITING) DIAG(F("ModbusIR: T%d F%d N%d %s"), _currentNode->getNodeID(), 0, _currentNode->getNumInputRegisters(), errorStrings[error]);
+      if (error != MODBUS_RTU_MASTER_SUCCESS && (error != MODBUS_RTU_MASTER_WAITING || _waitCounter > 2)) flagOK = false;
       break;
   }
   if (error == MODBUS_RTU_MASTER_WAITING) {