
ProDAQ 3020 USB 2.0 VXIbus Slot-0 Interface User Manual
3020-XX-UM
Copyright, © 2003 Bustec Production Ltd.
Page 29 of 60
Figure 24 - Using a basic I/O operation
As an example, you can use the viRead function to read data or a message from the
device. To do so, just specify the maximum number of bytes to read from the device and
press “Run”. As before, the VISA Assistant will show the message read as well as the
returned status of the operation.
2.7.2.3 Memory I/O Operations
The memory I/O operations consist of High- and Low-Level Access services. The High-
Level Access Services allow register-level access to devices that support direct memory
access. They encapsulate most of the code required to perform the access, such as
window mapping, address translation and error checking. The Low-Level Access Services
are similar in purpose, but are implemented without the software overhead of the High-
Level Services.
Figure 25 - Memory I/O Operations
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