VXI VT1422A - Manual (Page 152)

150 Programming the VT1422A for Data Acquisition and Control Chapter 4
The previous description is always true for a downloaded driver. In the
C-SCPI driver, however, the interrupts will only be enabled if cscpi_overlap
mode is ON when the enable command is given. If cscpi_overlap is OFF, the
user is indicating they do not want interrupts to be enabled. Any subsequent
changes to cscpi_overlap will not change which interrupts are enabled. Only
sending *OPC or STAT:OPER/QUES:ENAB with cscpi_overlap ON will
enable interrupts.
In addition the user can enable or disable all interrupts via the SICL calls,
iintron() and iintroff().
Creating and Loading Custom EU Conversion Tables
The VT1422A provides for loading custom EU conversion tables. This
allows for the on-board conversion of transducers not otherwise supported
by the VT1422A.
Standard EU Operation
The EU conversion tables built into the VT1422A are stored in a "library"
in the module’s non-volatile Flash Memory. When a specific channel is
linked to a standard EU conversion using the [SENSe:]FUNC:
… command,
the module copies that table from the library to a segment of RAM allocated
to the specified channel. When a single EU conversion is specified for
multiple channels, multiple copies of that conversion table are put in RAM,
one copy into each channel’s Table RAM Segment. The conversion
table-per-channel arrangement allows higher speed scanning since the table
is already loaded and ready to use when the channel is scanned.
Custom EU Operation
Custom EU conversion tables are loaded directly into a channel’s Table RAM
Segment using the DIAG:CUST:MXB and DIAG:CUST:PIEC commands.
The DIAG:CUST:
… commands can specify multiple channels. To "link"
custom conversions to their tables, execute the [SENSe:]FUNC:CUST
<range>,(@<ch_list>) command. Unlike standard EU conversions, the
custom EU conversions are already linked to their channels (tables loaded)
before [SENSe:]FUNC:CUST is executed, but the command allows the A/D
range for these channels to be specified.
NOTE
The *RST command clears all channel Table RAM segments. Custom EU
conversion tables must be re-loaded using the DIAG:CUST:
… commands.
Custom EU Tables
The VT1422A uses two types of EU conversion tables: linear and piecewise.
The linear table describes the transducer’s response slope and offset
(y=mx+b). The piecewise conversion table gets its name because it is
actually an approximation of the transducer’s response curve in the form
of 512 linear segments whose end-points fall on the curve. Data points that
fall between the end-points are linearly interpolated. The built-in EU
conversions for thermistors, thermocouples, and RTDs use this type of table.