How can know if the card in the socket of the cardreader?

Hi!
Thank you very much!I am sorry I didn't expatiate my question clearly to you.
As you know,even though there is not any card in the socket of the cardreader,when we attach the cardreader to
the PC,the OS can show us how many drivers this cardreader
has,such as:CARD(G),CARD(H),etc. And,as far as I know, the message WM_DEVICECHANGE must be broadcasted when the
cardreader attached to the PC,but after this,when you insert the card(s)(such as CF,MS,MFC,etc.) into the socket(s),I suppose there is not any message be broadcasted.Am I right?If I am wrong,then can you tell me which kind of message(or something else which can inform us that card(s) arrived) will be broadcast when the card(s) be inserted the socket(s) of the cardreader? If I am right,then can you tell me how can I know the card arrival and leaving?
Thanks!
Best wishes!

momer


[编辑 -  11/5/04 by  momer]

Hi!
Thank you very much!I am sorry I didn't expatiate my question clearly to you.
As you know,even though there is not any card in the socket of the cardreader,when we attach the cardreader to
the PC,the OS can show us how many drivers this cardreader
has,such as:CARD(G),CARD(H),etc. And,as far as I know, the message WM_DEVICECHANGE must be broadcasted when the
cardreader attached to the PC,but after this,when you insert the card(s)(such as CF,MS,MFC,etc.) into the socket(s),I suppose there is not any message be broadcasted.Am I right?If I am wrong,then can you tell me which kind of message(or something else which can inform us that card(s) arrived) will be broadcast when the card(s) be inserted the socket(s) of the cardreader? If I am right,then can you tell me how can I know the card arrival and leaving?
Thanks!
Best wishes!

momer
[编辑 -  11/5/04 by  momer]

I think the cardreader doesn't notify PC when you insert some card(s). Because the cardreader is just slave.
Maybe I'm wrong.