fix Modbus驱动功能码01、02、04存在的问题

Plugins/Drivers/DriverModbusMaster/ModbusMaster.cs

@@ -261,6 +261,7 @@ namespace DriverModbusMaster
                     }
                     else
                         ret.Value = retBool;
+                    ret.StatusType = VaribaleStatusTypeEnum.Good;
                 }
                 else
                 {
@@ -295,6 +296,7 @@ namespace DriverModbusMaster
                     }
                     else
                         ret.Value = retBool;
+                    ret.StatusType = VaribaleStatusTypeEnum.Good;
                 }
                 else
                 {
@@ -344,7 +346,7 @@ namespace DriverModbusMaster
                         if (FunCode == 3)
                             rawBuffers = master.ReadHoldingRegisters(SlaveAddress, startAddress, count);
                         else if (FunCode == 4)
-                            rawBuffers = master.ReadHoldingRegisters(SlaveAddress, startAddress, count);
+                            rawBuffers = master.ReadInputRegisters(SlaveAddress, startAddress, count);
 
                         var retBuffers = ChangeBuffersOrder(rawBuffers, ioarg.ValueType);
                         if (ioarg.ValueType.ToString().Contains("Uint16"))