Workstation CPU Requirements

It is important to note that running a trend can consume significant amounts of workstation CPU resources. Several factors can adversely affect the amount of CPU used:
  • The number of Pens/Tags being monitored
  • The frequency at which Pen's/Tag's data values change
  • The
    Time Span
    , as specified on the
    RSTrendX Properties X-Axis
     tab
  • The
    Period
    , as specified on the
    RSTrendX Properties Sampling
     tab
Sampled data points are first stored in workstation memory and then displayed on the screen. This consumes workstation CPU bandwidth. The less data that is collected, stored, and displayed, the less workstation resources are consumed. We therefore recommend that you configure your trend to use the minimal amount of workstation resources possible, while still meeting your application-specific requirements. To do this:
  • Configure the Time Span to be as short as is practical.
    For example, a 1-minute Time Span consumes less workstation resources than a 1-hour Time Span.
  • Configure the Period to be as long as is practical.
    For example, a 1-second Period consumes less workstation resources than a 10-millisecond Period.
A trend will automatically adjust to record fewer samples when data is not changing. Therefore, trending data that is not changing will require significantly fewer workstation resources than trending data that is constantly changing.
The following table provides some examples of recommended configurations. The following assumptions apply to this table:
  • The
    Logix Designer
     application is the only application running.
  • Workstation CPU utilization must remain, on average, below 80%.
  • Sampled data is changing constantly.
    Number of Pens
    Sampling Period
    Recommended Maximum
    Time Span (P5-90/32M RAM)
    Recommended Maximum
    Time Span (PII-300/96M RAM)
    1
    10ms
    3 Minutes
    15 Minutes
    4
    10ms
    30 Seconds
    3 Minutes
    8
    10ms
    15 Seconds
    100 Seconds
    1
    100ms
    45 Minutes
    2.5 Hours
    4
    100ms
    8 Minutes
    40 Minutes
    8
    100ms
    4 Minutes
    14 Minutes
    1
    1 sec
    15 Hours
    25 Hours
    4
    1 sec
    2 Hours
    7 Hours
    8
    1 sec
    45 Minutes
    3 Hours
    1
    10 sec
    4 Days
    10 Days
    4
    10 sec
    16 Hours
    75 Hours
    8
    10 sec
    8 Hours
    25 Hours
    1
    30 sec
    12 Days
    30 Days
    4
    30 sec
    2 Days
    5 Days
    8
    30 sec
    1 Day
    2 Days
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