Hi Rajavadivel,
You cannot do this in receiver file adapter to check the files exist in target directory and stop processing if there is any files in target directory, you can do control this in sender side by using start and stop the channel externally (The sender channel should be external control), sender application before sending to PI you can check the directory is there any files exist in the target directory or not, if the files there don't send the data, if there is files in the target directory then you can start the sender communication channel externally SAP PI : Start/Stop Communication Channel using WebserviceStart/Stop a communication channel from an ABAP program using the external control switch After sending the data you must stop the channel again.
Regards,
Praveen.