Detecting whether the card is present or not in a smart card reader
The code examples for the card reader is well hidden on their site. Nice products. hard to find docs.   Look for the smart card code examples.


And dont worry if you dont give us enough information, It was hard for me to find it too.

**'' Define Smart Card connections  
' allows non-contiguous pin usage  
  cd := cdpin 
 dira[cd] := 0 
 pub detect | ok 
'' Detects insertion and presence of Smart Card  
  if (ina[cd] == 1)               ' inserted?  
    start                         ' check card  
   ok := (write($A0) == ACK)  
   stop  
  else  
  ok := false  
 return ok  *


http://obex.parallax.com/objects/649/


http://www.parallax.com/Portals/0/Downloads/docs/prod/rf/32320-SmartCardReader-v1.0.pdf