retain timer values in eco plci

im using pm554 plc with hmi cp415.in my application i hav to enter the timer preset value via hmi and the condition is once timer value is entered the values should not change at any cause (i.e. should retain) i tried by declaring the variable as retain and persistent but didnt work. i read in manual that %RX can retain values in eco series plc but i tried with that and failed ,i even tried by moving the values to retained registers only on user condition but it too failed.is there any way to save the values in plc and load it again on next program start-up? Awaiting for reply!