Specifications

Chapter 9. Configuring the I/O Driver with the Power Tool 145
The access time in the driver is typically used with register blocks in the process
database.
NOTE: If you set the access time to Disabled, the driver does not switch to the
secondary poll rate nor stops polling if no one is requesting data.
Example 1
Datablock1
Primary poll rate = 10 seconds
Access time = 5 minutes
Analog Register block that references Datablock1 in its I/O address.
A FIX/iFIX picture with a data link to the Analog Register block.
When that picture is open and the WorkSpace is in the run-time environment, the Analog
Register block continually polls the driver for data. In this case, the driver does not stop
polling that datablock. Once the picture is closed, then 5 minutes later the datablock in the
driver stops polling. When the picture is opened again, the Analog Register block starts
requesting data from the driver and the datablock starts polling again. In this scenario, the
access time is used so that only the datablocks that have pertinent data to the open pictures are
polling, and the other datablock have either stopped polling or switched to a slower
(secondary) poll rate, whichever is configured.
Example 2
Datablock2
Primary poll rate = 10 seconds
Access time = 5 minutes
Analog Input that references Datablock2 in its I/O address
Scan time = 20 seconds
In this example, as long as the Analog Input block is on scan, it requests data from the driver
every 20 seconds. The access time never expires, since 20 seconds is less than 5 minutes.
Once the Analog Input block goes off scan, then after 5 minutes the driver’s datablock stops
polling. Once the Analog Input block goes back on scan, the driver’s datablock starts polling
again.