Assuming your talking about this device http://www.parallax.com/Store/Accessories/CablesConverters/tabid/166/ProductID/378/List/0/Default.aspx?SortField=ProductName,ProductName then it's not really suitable. Your better off looking for a TTL to RS232 device like this http://www.ebay.co.uk/itm/RS232-Shield-Arduino-TTL-UART-Port-RS232-/261105132922?_trksid=p3284.m263&_trkparms=algo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BIEW%252BFICS%252BUFI%26otn%3D21%26pmod%3D261119405859%26ps%3D54 or http://www.ecrater.co.uk/p/12274564/mini-max3232-rs232-shield-board#