Global data in S7 300

Hi,

1) How to declare a global variable data in S7 300.. like if I declare a variable in FC, then it holds good for the FC only.. If I declare it in OB1, is it a global variable or a local variable?

2) How to calibrate an analog input in CPU 224XP (s7 200) which has built in Analog input and output?

Thx in advance
Sudheendra

For S7300 global data use data blocks and/or M flags.