Adjusted mutex lock and delay for modbus

lib/TEMP/R4DCB08_Driver.h

@@ -25,7 +25,9 @@ namespace drivers
             T_MAX
         };
 
-        const uint8_t maxRetries = 5;
+    private:
+        const uint8_t c_maxRetries = 5;
+        const uint32_t c_minDelay = 500;
         const uint16_t REG_TEMP = 0x0000;
         const uint16_t REG_TEMPCORR = 0x0008;
 
@@ -41,9 +43,13 @@ namespace drivers
 
         const uint8_t getNum();
 
+    private:
+        void delayRequest();
+
     private:
         const uint8_t m_address;
         uint8_t m_sensors;
         MODBUS &m_bus;
+        uint32_t m_lastRequest;
     };
 }