Hello everyone

please help me to fixed not real reading of ET 200SP Analog input module AI 8xRTD/TC 2-wire HF (6ES7134-6JF00-0CA1) card , I connect TC type K sensor to this card and do all configurations but the reading is not real and the sensor read (-8) - it must be 270 or 280 because the room temp. is abut 27 C . 

AI card installation on ET200SP IM 155-6 PN ST , please help me to solving this problem and get correct reading from AI module.  

Hi EngSamer,

For an S7-1200/S7-1500 controller in STEP 7 (TIA Portal), how do you scale integer values in real numbers and vice versa for analog inputs and outputs?

Hi,

in general it is not necessary to "scale" the input value for thermocouples/RTDs. The value in the cannel must only be devided by 10. So 27°C would be dec. 270 in the channel.

Issue:

The topic with thermocouples was already discussed many times in this forum and several things have to be checked. To give a complete overview of all possible solution you probably can write a book again and again, so check the other posts.

ET200SP:
The most common issue is the reference junction/compensation because this is depended on the used BaseUnit! Only BaseUnit "A1" does have the internal temperature sensor which can be used as reference junction (internal). If you use a BaseUnit "A0" you can not use the parameter for the internal reference junction/compensation (even if its possible to configure in hw config).

If BaseUnit A0 was used, you need another compensation method, for example via an additional PT100. (Same thing If the wires were extended via "standard" copper wires in an external cabinet, you can not use internal reference junction even if BaseUnit A1 was used).

Check this FAQ:

What do you have to watch out for when using thermocouples if the expected value is not displayed?

 Other things to check:

• Is the thermocouple connected to the BaseUnit directly? Because the wires were extended via "normal" copper wires in an external cabinet this will not work! thermocouples need special wires, compatible with the termocouple type.
• Insulated thermocouple or non insulated thermocouple? Check the wiring and grounding accordingly.

Old posts:

Thermocouple Type J

6ES7134-4JD00-0AB0 Thermocouple K reading are incorrect

There are many more to the same topic...

regards

sancruz