Hi
Check these links/threads, i would suggest you to explore the forum before posting a question. I believe your query would have been answered already somewhere.
if you still dont find a answer, you've to probably post this question in ABAP technical group.
How to read order details from the liveCache with FM /SAPAPO/OM_ORDER_GET_DATA
https://scn.sap.com/thread/1328885
APO-Technical - Supply Chain Management (SCM) - SCN Wiki
How to read data form livecache
SAP SCM APO SNC: Functional Modules, BAPI, BADI, User Exit in APO/SCM
Just my thoughts
Vinoth