Hi Mary – One of the institutions I do contract work for uses these. I can try to help – do you have the instruction manual? If not, you can access it here: http://www.az-instrument.com.tw/upload/product_pdf/pdf/ODgxOCBTRVJJRVMoVk1VODgxOEFaKQ==-1268989943-Ht3xB.pdf and the CD that comes with it also has a downloadable version that is more detailed, I believe.
Catherine
