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Principles of Operation
19
Block and list loop operations are very similar in operation. The main difference is that block
loop uses only two block buffers, which are automatically allocated and managed, while list
loop uses a linked list of as many buffers as you want, but your program must allocate and
free each buffer appropriately.
Scan Loop Operations
Use software to start a scan loop operation. When it detects a trigger event, the module
continuously acquires an input scan record and/or outputs an output scan record on each
pulse of the sample clock, until you stop the operation. Refer to
for more information
on input and output scan records.
The sample rate is determined by the frequency of the sample clock and is the rate at which a
single input scan record is acquired and a single output scan record is output; refer to
for more information on the sample clock.
Block Loop Operations
Use software to start a block loop operation. When it detects a trigger event, the module
continuously acquires input blocks and/or outputs output blocks until you stop the
operation.
Each input block consists of the following information:
• Input scan records; refer to
for more information on input scan records
• The number of scans in each block
• A flag that indicates whether or not the block is full
• A pointer to the next block
Each output block consists of the following information:
• Output scan records; refer to
for more information on output scan records
• The number of scans in each block
• A flag that indicates whether or not the block is full
• A pointer to the next block
List Loop Operations
To perform a list loop operation, use software to allocate a linked list of input and/or output
blocks, and start the list loop operation. When it detects a trigger event, the module acquires
lists of input blocks and/or outputs lists of output blocks. Each list contains a specified
number of input and/or output blocks. Refer to
for more information on input and
output blocks.
You can specify whether to stop the operation when the number of blocks have been filled (for
an input operation) or emptied (for an output operation) or whether to continue the operation
starting by overwriting the first block in the list.
When you are finished acquiring and/or outputting data, you can use software to stop a
continuous operation and free the previously allocated memory.
Summary of Contents for DT9840 Series
Page 1: ...DT9840 Series UM 19197 T User s Manual Title Page ...
Page 4: ......
Page 44: ...Chapter 1 44 ...
Page 76: ...Chapter 2 76 ...
Page 98: ...Appendix A 98 ...
Page 124: ...Appendix B 124 ...