The software side of the control system used a program called LabVIEW: a visual (or function block) based coding language used for system design and development. The full LabVIEW programme can be seen below. All data enters or leaves the USB6008 via function blocks called ‘DAQ assistants’ and have been labelled in a consistent manner, for example ‘’6008 (1) Input’’.

The data streams coming from the sensors were sampled four times per second (0.25s) and are then manipulated to give steady, calibrated readings in °C or relative humidity. All sensors (aside from T10) were subjected to an average of the last 8 values in order to reduce the rapid fluctuations in voltage that were present. T10 was required to react quickly to temperature changes as it controls the flow temperature and therefore only the last 4 samples were averaged.

The temperature sensors produce 10.0mv/ °C and as such were multiplied by 100 to give a value in °C. After this the signals were offset as required – as discussed under calibration. The humidity sensor had to be offset and then scaled, it registers zero humidity with 0.958V and then increase by 30.68mW/%RH. As such 0.958 was subtracted from the signal after which it was multiplied by 32.59.

The sensor readings were then fed to function blocks to display them as both numerical values and graphical plots, allowing monitoring mid-test. Logging functionality was employed by the use of a “Write to Measurement File” block: this appended the sample values to a text file for exporting to Excel. The data could be taken as a ‘snapshot’ by the use of the ‘’OK’’ button attached to the write block or recorded continuously by removing the “OK” button.

The T10 signal is then compared to three separate set values. In this case the system is set up to converge on 24°C so these three values are staggered - the system calibration sub page linked here discusses the logic behind this and gives an indication of the system response. When the temperature is less than these values then a logic state 'high' is generated (indicated by green “LED” indicators). This Boolean signal is sent to the “6008 (2) Output” block causing the USB6008 to send the signal to switch the relays, allowing current to flow to the heaters. It should be noted that the Boolean signals are also recorded by the “Write to Measurement File” block.