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Controllers FAQ

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Controllers FAQ

The following causes are possible. Please check them.

1.Is the correct input type being used for the Temperature Sensor?

(Check the Temperature Sensor input type setting)

2. The lead wires and the power line for the Temperature Sensor are routed through the same conduit, so the lead wires are affected by noise from the power line. (Ordinarily, this causes the display value to change erratically)


Route the lead wires and power line separately or shorten the wiring path.

3. The temperature controller and thermocouple are connected with copper wire


Either connect the lead wires of the thermocouple directly, or connect them using compensating conductors that suit the thermocouple.

4. Check to make sure that the measurement location is appropriate for the temperature sensor

5. Are you sure that a temperature offset has not been set?

ON/OFF control action turns the output ON or OFF based on the set point. The output frequently changes according to minute temperature changes as a result, and this shortens the life of the output relay or unfavourably affects some devices connected to the Temperature Controller. To prevent this from happening, a temperature band called hysteresis is created between the ON and OFF operations.

Hysteresis (Reverse Operation)

RTD- PT100 Sensor

All three lead wires used for extension must have the same resistance and the same length. The extension will cause the resistance of the lead wires to affect the display temperature, so use lead wires with thick conductors. (OMRON does not carry lead wires for extension. Use commercially available lead wires.)


Be sure to use compensating conductors for the extension. Also, select compensating conductors that suit the characteristics of the thermocouple. Do not extend the lead wires with compensating conductors that do not suit the characteristics of the thermocouple , or with ordinary lead wires, as this would prevent proper temperature measurement. Be sure also to connect the wires using the correct polarity (+/-)

ON/OFF control action a temperature rise that exceeds the set point after temperature control starts is called overshooting. Temperature oscillation near the set point is called oscillation. Improved temperature control is to be expected if the degree of overshooting and oscillation are low

Thermocouple temperature sensors are constructed using two dissimilar metals that are joined together. The junctions are called the measuring junction and the reference junction (output terminal side). A thermoelectromotive force is generated between the junctions with a fixed correlation to the temperature providing the difference in temperature.

Therefore, the temperature at the measuring junction can be determined from the thermoelectromotive force when a fixed temperature is maintained at the reference junction.

Thermocouple temperature sensors are capable of measuring the highest temperatures among contact temperature sensors by using this measurement method.

The Auto tuning process is performed at set point. Temperature will oscillate around the set point during the tuning process. Set a set point to a lower value if overshooting around the normal process value is likely to cause damage. To start the auto tuning process, set the set point properly, select the parameter A.TUN (A.TUN) in the program menu set it to YES.

After auto tuning procedures are completed, controller will revert back to the PID control by using the new calculated PID values. The PID values obtained are stored in the non-volatile memory.


If Ramp function is used, it will be disabled once the auto tuning starts. The auto tuning is cancelled as soon as either failure mode or manual control mode occurs.

Auto-tune function: Auto tuning is a function with which the controller automatically measures the process characteristics to automatically set the optimum PID constants. Limit cycle method is used to calculate the PID values.

Auto tune function is not available for valve position feedback and valve position without feedback PID control type.

Check the mains Cord.  I/P power may not be present. Check the power supply voltage is proper as per requirement

Is the connection as per polarity?

Check the connection diagram from the operational manual

Is input resistance connected to the terminal?

Connect 250Ohm/100 Ohm resistor connected as per operational manual

Is instrument configuration as per requirement?

Check the input type/ range low and high setting/Input L and Input H parameter

Is the connection as per polarity?

Check the connection diagram from the operational manual D+ and D-

Is the modbus parameter for serial communication configured properly?

Check the serial No. and baud rate settings at master device and slave device

If you forget the password for the device then use master password to enter the mode.

Take a master password from the customer support department.

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