VXI VT1422A - Manual (Page 164)

162 Advanced Programming with the VT1529B Chapter 5
The VT1529B provides the flexibility to make all of the measurements
normally needed for structural test applications without the need for other
SCPs: strain, temperature and dc voltage (from string pots or dc-dc LVDT).
The VT1529B also allows channels to be dedicated to the strain excitation
voltage and includes these channels in the scan list so that the excitation
voltage is measured during every scan. The updated reference
measurements can be used in the strain engineering units conversions,
yielding more accurate data.
With the VT1529B option 002 VT1586A-to-VT1529B cable, the VT1586A
Rack-Mount Terminal Panel can be connected to the VT1529B yielding an
accurate and dependable isothermal reference needed for thermocouples.
Finally, the VT1529B is 100% backwards compatible with the VT1529A so
programs written for the VT1529A will work unchanged with the VT1529B.
This chapter only describes the new capability of the VT1529B.
Note
The new capability is available only through the VXIplug&play driver and
only with direct VXI interfaces (VXI embedded PC, MXI-2, or Agilent/HP
E8491B IEEE-1394 PC Link to VXI). The new capability is not available
using GPIB and the Agilent/HP E1406A VXI Command Module.
Changes to the Use Model
There are some important changes in the way the VT1422A works with the
VT1529B when these new features are used. Note that these changes affect
only the new features; if the new features are not used or desired, the
VT1422A operates exactly as described in the previous chapters.
The first thing to know is that, as noted above, the VXIplug&play driver
must be used in order to use the new features and that these features are not
available with the Agilent/HP 1406A VXI Command Module. A direct VXI
interface must also be used such as a VXI embedded PC, MXI-2, or the
Agilent/HP E8491B interface.
Engineering Units
Conversion Done in
VXIplug&play Driver
All of the new functionality is implemented by the VXIplug&play driver.
The on-board DSP code of the VT1422A has not been changed and this
has a significant impact on the use model. In particular, on channels
programmed using the new features, engineering units conversions are
performed by the driver, not by the on-board DSP. This means that all FIFO
and CVT data for these channels will be voltages, not engineering units.
Additionally, if algorithms have been downloaded into the VT1422A, the
channel values provided to the algorithms will be voltages, not engineering
units. If the algorithms require engineering units, either the engineering
units conversions in the algorithm code must be performed or the algorithm
must be modified to accept voltages.