Requirements

The normal average number of time stamped events detected per second in the installation needs to be estimated by the user in order to define the communication parameters.

Based on the normal number of events, the user sets:

OFS Performance

OFS communicates with several PLCs and devices. The assumption is that 50% of the PC resources are used by OFS and 50% are used by AVEVA Plant SCADA.

A dedicated tool (OFS TimeStamp Helper) is used to estimate the event detection capability depending on the polling rate chosen. This tool is located on the OFS installation DVD.

OFS TimeStamp Performance Helper Tool Purpose and Use

OFS TimeStamp Helper tool is intended to help you to define OFS setting parameters when it is used in a configuration with time stamping solution.

NOTE: .NET Framework 3.5 Service Pack 1 or higher is required to run OFS TimeStamp Helper.

The Configuration tab allows to configure OFS TimeStamp Helper tool. When the cursor points to a spin box with a value to be entered, Minimum and Maximum values are displayed in a dialog box.

  • In Configuration > General specify the number of PLCs included in the installation.

  • In Configuration > PLC Configuration : > PLC n°x specify the parameters for each PLC of the installation.

The Results tab displays information provided by the OFS TimeStamp Helper tool. When the cursor points to a result dialog box, the value Limit is displayed in a dialog box. If the limit value is exceeded the dialog box border is displayed in red.

  • Recommendation on normal number of events detected per second.

    According to the hardware architecture and the associated OFS time stamped events polling rates, the tool provides a recommendation on the normal number of events detected per seconds that should be targeted in order to be able to manage additional temporary bursts of events stored in the buffer.

    This information appears in the following folders:

    • Results > PLC Results : > PLC n°x > CPU, or BMX CRA, or BMX ERT

      Number of events detected per second per CPU, or CRA, or ERT

      CPU: Computed polling rate in ms

      CRA or ERT: Total number of events detected per second per PLC

    • Results > General

      CPUs Total number of events detected per second

      BMX-CRAs total number of events detected per second (for all PLCs)

      BMX-ERTs total number of events detected per second (for all PLCs)

  • Estimation of the time needed to read a full buffer.

    After a temporary burst or after a particular operating mode such as a cable disconnection between the time stamping source of events and OFS, the event buffer can become full. The tool provides an estimation of the time needed to read this event buffer and to come back to a normal situation in which the system runs with the normal number of events per second. The time to read the buffer depends on the OFS time stamped events polling rate (buffer output flow), the number of events stored in the buffer and the normal number of events per second (buffer input flow).

    This information appears in the following folder:

    • Results > PLC Results : > PLC n°x > CPU, or BMX CRA, or BMX ERT

      Time to read full buffer in second

      NOTE: For a BMX ERT 1604 T, Time to read full buffer in second is a minimum value because the tool considers that there is 1 event in each of the 255 groups of the BMX ERT 1604 T buffer. A group is a set of 1 to 16 events detected in the same cycle. If 16 events are detected in each group, the Time to read full buffer in second value has to be multiplied by 16.

  • Estimation of the total OFS bandwidth (msg/sec).

    The tool provides an estimation of the total OFS bandwidth (msg/sec.) used to read the normal number of events per second on all PLCs and it checks that the estimated bandwidth does not exceed the maximum OFS bandwidth allocated to read events.

    This information appears in the following folder:

    • Results > General

      OFS bandwidth used to read events (msg/s)

  • Total number of time stamped I/Os in 1 PLC.

    This information allows to check that the maximum number of configured time stamped I/Os is not exceeded.

    This information appears in the following folder:

    • Results > PLC Results : > PLC n°x

      Total number of time stamped IOs on one PLC