The Hydra Data Acquisition Unit (DAU) is a GPIB (IEEE-488) instrument.  That means that it can take data under computer control and can send that data back to the computer.  (Click here for an introduction to IEEE-488 instruments.)  Here, we will examine how to reset the Hydra in a LabView vi.  That LabView vi is ResetHydra.vi.  Then, we will examine taking a single temperature measurement in a LabViewvi, 1TempHydra.vi.

        To reset the Hydra, all you have to do is:

Reset the Hydra by issuing an *RST command.

        To reset the Hydra, all that is necessary is to issue a *RST command.  Here is the LabView code that does that.

In this LabView code, the following occurs.

• The action takes place in a GPIB Write block.  The GPIB Write block is found in Instrument  I/O - GPIB - GPIB Write on the Functions Palette.  Note the following for the GPIB Write block in the reset vi.
• The address for the Hydra is assumed to be 3.  That's the string constant (pink box) in the diagram.  Check the Hydra to ensure that the IEEE-488 address is set to 3.  Most software in the EE labs assumes that address for the Hydra.
• A *RST command is written to the Hydra (at address 3).
• In other words, a four character string - *RST - is sent to the computer via the connecting cable.
• The mode is set to 3.  That's the numeric constant (blue box) in the diagram.  Mode 3 does the following.
• Appends CR (Carriage Return) and LF (Line Feed) to the string (*RST) and sends EOI with LF.
• The GPIB Write block generates an error signal - which should indicate no error if all goes well, i.e. if the instrument is connected and the address is correct, etc.) - and that error can be used by later GPIB blocks to determine their actions.  In the ResetHydra vi, that error signal is the output of the vi.