32
•
Using the DAS-1700 Series with DriverLINX
Keithley DAS-1700 Series
The following list explains the Event abbreviations in the preceding table:
•
null—Null or None Event when a Service Request doesn’t require an
event
•
cmd—Command Event when DriverLINX starts or stops a task on
software command
•
TC—Terminal Count Event when DriverLINX processes all data
buffers once
•
rate—Rate Event specifies how DriverLINX paces or clocks data
transfer
•
dig—Digital Event specifies a trigger, clock, or other control signal to
pace, start, or stop a task
Logical Channels
DriverLINX designates the individually addressable hardware channels for each
subsystem as “Logical Channels.” Generally, the zero-based Logical Channel
numbering sequence closely follows the hardware manufacturer’s channel numbering
scheme.
In some cases, however, DriverLINX assigns Logical Channel numbers to hardware
features that users don’t commonly think of as “channels.” For instance, DriverLINX
commonly models external hardware clock input lines, external hardware trigger
input lines, and external interrupt inputs as 1-bit digital Logical Channels. In other
cases, DriverLINX models subsystem-specific features, such as internal pacer clocks,
as members of a more general-purpose set of counter/timer channels.
For a list of DriverLINX assigned Logical Channel numbers, see the notes on each
supported subsystem.
Buffers
Applications usually use data buffers to exchange data between the application and
the data-acquisition hardware. When using data buffers, please note the following
points about DriverLINX’s data buffers:
•
DriverLINX supports data-acquisition tasks with 1 to 255 data buffers
per task.
•
DriverLINX imposes no size limits on a single buffer, although the
operating system or some hardware products may have size restrictions.
•
User applications must allow DriverLINX to allocate all data buffers to
guarantee application portability to different hardware and operating
systems and to insure that the hardware can physically access the buffer
memory.
•
User applications usually don’t have concurrent or immediate access to
the in-use data buffer while DriverLINX is executing a data-acquisition
task.
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