Measurement Computing LabVIEW Rev.3.0 - Manual (Page 15)

IOtech LabVIEW Substitution VIs 10-03-02 4-1
Issues and Caveats 4
Intended Use – IOtech LabVIEW Substitution VIs are intended for LabVIEW users who are replacing one of the
following devices with an IOtech DaqBoard/2000 Series board.
• National Instruments “E” series board
• PC-LPM-16
• AT-MIO-16 “H” or “L” series board, with this exception, IOtech LabVIEW Substitution VIs
do not support the x500 gain-setting on the AT-MIO-16 L board.
If you need to access the full functionality of DaqBoard/2000 Series boards,
the IOtech LabVIEW API VIs must be used.
No Signal Conditioning DBK Support – Architectural differences exist between IOtech and National
Instruments boards. For this reason, certain features that are available in DaqBoard/2000 Series boards
[and in National Instruments boards] are not supported by the Substitution VIs. For example, the
Substitution VIs do not support DBK signal conditioning options .
DSP – Some of the Low Level NI-DAQ VIs reference DSP handles to buffers. The DSP handle functionality is
automatic in the DaqBoard/2000 Series and the VI DSP handles are simply ignored.
Any VIs that are dependant on reading from or writing to a buffer [using either a DSP handle or a buffer
offset] will not function properly when replaced.
Trigger Types – Attempting to use a trigger type that is not supported will result in error 10083. Refer to
DaqBoard/2000 Series documentation for a list of valid trigger types.
Analog Input Range Settings – It is often the case that IOtech and National Instruments devices have different
range and gain settings. Gain selection for DaqBoard/2000 Series boards is automatic and is based on the
user-selected voltage limits.
Analog Output – Live update of an output buffer is not supported. If an output buffer needs to be changed, then
the output must be stopped, changed, and restarted.
Counters and Timers – Low-speed frequency measurement and signal timing can be accomplished with the
examples located under the IOtech CTR VI Palette. The support of this section is restricted to event
counting in 16-bit and 32-bit counter lengths. Frequency measurements can be made using event counting
within a known time frame. See the “Measure Frequency.vi” within the IOtech CTR Palette under
examples.
The CTR example VIs are NOT exact replacements for NI-DAQ VIs and will require program
modification if they are to be used. You can run the examples to determine application suitability.
Pulse and Square Wave Generation – Pulse and square wave generation are limited with the IOtech
DaqBoard/2000 Series boards. Square wave generation can be accomplished with the example square wave
generation VI located under Digital IO.
The square wave generation VI example is NOT an exact replacement for NI-DAQ VIs and will
require program modification if it is to be used. You can run the example to determine suitability for
your application.
Analog Output VIs can provide functionality for applications that make use of one-shot pulse or square
waves with asymmetrical duty cycles.