The Hydra Data Acquisition Unit In LabView - Resetting The Hydra
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
Then, we will examine taking a single temperature measurement in a LabViewvi,
To reset the Hydra, all you have to do is:
Reset the Hydra by
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.
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.
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.
is set to 3.
That's the numeric constant (blue box) in the diagram. Mode 3 does
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.