Agilent Technologies E4370A, E4371A Calibration, cfSelftest, cfReadTestLog, cfCalStandard

Programming Overview - 5

Selftest

The Agilent E4370A MCCD has a built in selftest capability, which is performed at power-on. This limited selftest verifies proper operation of the memory functions, serial communications functions, analog-to-digital converter functions, and the voltage programming of each output regulator. The selftest also checks for the presence of an external dc source on the power bus. The test applies no power to the cells and is performed whether or not cells are connected to the Agilent MCCD.

A more complete selftest can be done by executing the following command:

cfSelftest();

In addition to performing most of the power-on tests, cfSelftest() also tests the current measurement functions as well as the constant current charge and discharge functions of every output regulator.

CAUTION: cfSelftest() causes voltage to be applied to the outputs. Make sure that no cells are connected when executing cfSelftest().

Since selftest can take many seconds to complete, the cfSelftest() function does not wait for selftest to complete. It returns immediately after starting selftest. During selftest, the CF_SELFTEST_STAT bit is true in the status word returned by cfGetInstStatus(). When selftest is finished, CF_SELFTEST_STAT goes false, and a test failure is indicated by the status bit CF_SELFTEST_ERROR_STAT. This means that you can poll the instrument status while selftest is running to determine if selftest is complete.

If there are any selftest errors indicated by the CF_SELFTEST_ERROR_STAT bit, then the details of those errors can be obtained from the test log. The test log is read using

cfReadTestLog();

The test log retains the selftest error information until another selftest or a calibration command is given.

Calibration

Calibration of the Agilent MCCD can be performed only when the Agilent MCCD is in the CF_IDLE state (see Figure 5-3). Complete information on calibration is provided in Appendix B. Briefly, calibration is a two-step procedure. First the internal references are calibrated using an external DMM, and then the internal references are used to transfer calibration to each channel. You must always perform the second step when you install a new or a repaired charger/discharger card in the mainframe.

To calibrate the internal mainframe references you must connect a voltmeter to serial port A as described in appendix B. To begin mainframe reference calibration, use:

cfCalStandard();

To transfer the standard references to each channel, all external connections to the cell outputs and sense terminals must be open. The function to begin transfer calibration is:

cfCalTransfer();

The combination of cfCalStandard() and cfCalTransfer() can be performed with the single command:

cfCal();

CAUTION: Make sure that no cells are connected when executing cfCalTransfer() or cfCal().

63