I want make sure idftp.abort is fininshed in IDFTP

I use three idftp thread to download one file form ftpserver
I abort idftp1 and restart idftp1 from other positon.
but when I retr file, idftp.abort not finished.
I get these Info: EidProtocoReply with Message '226 ABORT ...'
I use IdLogftp3 to get ftp Log:
last three lines are:
ABORD
226 ABORD SUCCESS
PORT 61.171.......
so I have to delay 2 sec ,then use idftp1.abort.
but not so good.
plz tell me How to confirm .abort is finished?
thanks!