Function Retain

hello all,

I have a problem to retain a value in the HMI screen. I have a parameter called "temperature = (value)" and another for "Humidity =" (value) ", but when the system shuts down or have a power outage in the sector, the value specified in the" temperature and humidity. "Not are registered. therefore have to put back the value.

I have a "PLC tag" named SPT = SET POINT temperature and SPU = SET POINT humidity, which try to retain them, but I can not just these two items. Whenever you use the "retain" it selects other tags together.

How do I retain only those values​​?

Thank you and I await answers ..

Best Regards,