Data Transfer Optimization

This section describes the data transfer optimization implemented for the Gem80Scanner. Optimization is the means by which the scan task seeks to minimize the load on the communication channel by making scan device requests more efficiently.

The aim of optimization is to include as many scan input records in a single request as possible, thus reducing the communication overhead.

Writes are not optimized since writes to a scan device typically occur much less frequently than polls or reads.

Follow these guidelines, whenever possible, to minimize communication overhead:

1. keep "data" and " table number" together in the scan input table,
   
2. order scan input table " table number " in ascending order,
   
3. eliminate gaps in " table number "; if one/two table values are not required, configure them into the scan input table anyway (make sure they are enabled),
   
4. assign the same poll type to groups of records that have consecutive " table number ",

Use the "max tbl count" attribute to control how many table values are requested for in a single request.

The scan task will break a group of scan input records if one of the following conditions exists:

1. different "type" value
   
2. the "table number" is sequential