Device group definitions

The Device Groups dialog box, which appears by clicking the Device Groups tab in the Legacy or the Symbolic configuration view, is the place where you create, add, delete, and define device groups. You can also configure default update intervals for the objects and edit update intervals in this dialog box.

Note: When you select another part of the Server tree hierarchy, you are prompted to save the modifications to the configuration set.

Create or add device groups

1. Right-click in the Device Groups box and click Add.

2. Enter a unique name for the device group. Device group names are case-insensitive.

Delete device groups

• Right-click on the device group to be deleted from the list and select Delete.

Edit device groups

3. Right-click on the device group to be edited.

4. Select Edit from the menu to open the Device Group Parameters dialog box.

   

5. Make the necessary edits.

Note: The Edit option is enabled only for Legacy connection.

The Edit dialog box contains four configurable elements:

• Cyclic Services
  If you use Cyclic Services (the Disable S7 cyclic service option is not selected), configure two additional settings:

  • Maximum available

  • Limit cyclic services to

    If you know how many services the remote PLC can handle, you can limit the use of cyclic services in this device group and distribute the available cyclic services among the device groups associated with this connection. Otherwise, you can use the maximum available services.

  • Allowable range for Limit cyclic services to is 1 to 150.

  • The default is 1.

    Click on Disable S7 cyclic service to disable the S7 cyclic services for the device group.

  • Cyclic services have a reliable update frequency and need less bus access. They are a limited resource in the PLC and/or Communications Processor.

    If you select the Disable S7 cyclic service option, the SIDirect Communication Driver to read input and output blocks (also peripherals) if their address spaces are not contiguous.
    Select this check box if you have some holes in the input-address or output-address space in your PLC.

• Optimization
  Select one of the following settings to configure the optimization mode the SIDirect needs to use to acquire data from the PLC:

  • S7 SAPI

  • Block read

  • Auto

    The default is Auto. For more detailed information, see "Optimization Considerations".

    Note: The S7-1200 and S7-1500 PLCs do not support SAPI.

• Block Services
  Communication DriverIf the Block Services function is required, you have to configure two settings in the Block Services box:

  • Initial Values Timeout
    Allowable range for Initial Values Timeout is 0 to 65,535 milliseconds; the default value is 5,000.

  • Update Timeout
    Allowable range for Update Timeout is 0 to 65,535 milliseconds. The default value is 5,000.

    The Block Services function needs time-outs to supervise reading initial values and updating the block items to this connection. A time-out value of 0 (zero) disables the time supervision of block messages.

    Block services are unconfirmed services. If the remote station does not send data within this time range, the Block Services is reinitialized and an error message appears in the Logger.

Configure default update intervals

• To configure a default update interval for the object, right-click in the Device Groups box and click Config Default Update Interval on the menu.

Edit update intervals

• To edit the update interval for an object, double-click its value in the Update Interval column and make the edits.

  • Update Interval is the frequency in milliseconds that the SIDirect Communication Driver acquires data from the topics associated with that device group.

  • Different topics can be polled at different rates in a PLC by defining multiple device-group names for the same PLC and setting a different Update Interval for each device group.

Note: When you select another part of the SIDirect Communication Driver tree hierarchy, you are prompted to save the modifications to the configuration set.