The interface between the switching matrix and the computer is a National Instruments PC-DIO 24 ISA card. The card has a 40-way connector. A ribbon cable is used to connect to the identical socket on the switching matrix.


The software used to control the interface is currently under development using Labview. The latest version of the program can be downloaded via the following link :-

soaktest.zip(372kB)

The ZIP file contains several labview programs which can control the switching matrix, take readings from a Keithley 617, 2410, or similar meter, control a Bertan 225 series or Keithley 2410 power suply, and make use of an HP34970A datalogger with 20-channel multiplexer card, all via an IEEE-488 connection. The file should be downloaded and unzipped to a suitable place on your hard-drive. The main program is called soaktest.vi and this is the one which should be opened and run.

The front panel has a button which must be set to run when the application is running and will stop the application cleanly when switched to stop. Names should be given for the detectors in the correct location boxes. The program will automatically measure only the channels for which a name is given. The software can be used for soaktesting a single detector without the switching matrix by un-checking the appropriate box.

The channels of the datalogger can be set individually for temperature or humidity measurements using 4-wire PT-100s thermistors or Honeywell HIH-3605 capacitive humidity sensors respectively. The length of the test can be set and the program will automatically end when this time is reached. An indicator on the front panel shows the time which has elapsed since the test began. The sample period determines how often the currents, temperatures and humidities are measured and the log period determines how often the are written to the datafile.

A current limit can be set. If any of the channels exceed this limit the program will ramp the voltage to zero and stop immediately.

There are also four graphs on the front panel. The first graph shows the latest measured values of the currents on each channel in mA. The second graph shows the history of any one channel chosen by the user and is updatedeach time the values are logged. The other two graphs show the temperature and humidity measurements.


The following diagram shows how the switching matrix is connected to the detectors and to the ammeter. It also shows how the tri-axial nature of the connections is mainained (as closely as possible) throughout. It does not show the connection to the computer which is described above.


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