Each Peltier-controlled cuvette holder manufactured by Quantum Northwest is shipped with a temperature controller (for example, model TC 1, TC 125 or TC 425). The cuvette holder may be operated manually using the buttons on the front of the controller. PC control of the cuvette holder is also available with the purchase of the T-App program. The temperature controller is then connected to the computer via a USB port, in addition to its connection to the cuvette holder. T-App software provides functions required for accessory programming, as well as the setting of temperature points, ramping, and monitoring experimental temperature with time. The temperature controller accepts simple text commands from the computer through a serial interface, so complete control can also be available from user-written programs. Serial control commands are provided as appendices to our product manuals. Please ask us for more details.