The present invention provides a method of operating a thermal cycler using readable tags (for example, Radio Frequency Identification (RFID)) to simplify the operation and to reduce user interaction requirements. The RFID tag is used to program the thermal cycler unit. This automates process flow and allows single button operation. In general terms, the invention uses RFID tags provided on reaction vessels to identify a particular vessel; while a readable program card contains data associating reaction vessel identities with specific operations (eg, thermal cycling program, detection steps) to be performed on that vessel. The thermal cycler detects the reaction vessel RFID tag, and selects an appropriate operation to perform.