immediate access of i/os of s7300 plc

We have s7300 plc cpu315-2 PN/DP and s71200 plc cpu1214 dc/dc/rly in lab.

In s71200 plc for immediate accessing the input/output we can put ":P" at the end of corresponding tag so that i/os will be read write directly from source instead of from input or output memory image of plc.

But in s7 300 plc to make input/outputs immediate when we append ":P" to input/output tags, it doesn't support it.

can you help us how we can make i/os immediate in s7300 plc so that it will always immediately read or write those i/os without waiting for scan cycle.

Please help

thank you