About DeviceNet I/O configuration

In a DeviceNet I/O configuration, a communications interface card (called the DeviceNet Scanner, 1784-PCIDS for the desktop, 2711P-RN10H, 2711P-RN10C for the
PanelView Plus
 device) is physically attached to the host computer upon which the
FactoryTalk Linx
 server is running. This DeviceNet communications interface card is configured by
RSNetWorx for DeviceNet
 to exchange I/O data as a Master (scanner) and/or Slave (adapter) device on the DeviceNet network.
FactoryTalk Linx
, in turn, is configured to access the I/O data resident on that locally attached DeviceNet communications interface.
IMPORTANT:
  • The support for DeviceNet I/O communications for the desktop has been tested for use in application development and application test environments only. Use this functionality only in a hazard-free, non-production environment. Failure to observe this precaution could result in damage to equipment, severe bodily injury, or loss of life.
  • A value of 0 is assigned to any bit in the output table whose value has not been user-specified. Therefore, if an output alias does not have an initial value specified, or if an alias has not been defined for an area of the output table, a value of 0 will be assigned to it, and a warning message will be displayed. However, the DeviceNet Scanner will still be able to enter run mode. You must be aware of the effect this may have on the output devices in your application since a value of 0 is applied immediately when the DeviceNet Scanner goes into run mode.
  • Under certain conditions, due to the upper bandwidth limit of the DeviceNet protocol, overuse of change-of-state (COS) connections can disrupt the network. Extensive use of COS connections, particularly with rapidly changing data, can adversely impact the available bus bandwidth. If the bus bandwidth becomes entirely consumed, some devices may only be able to communicate intermittently. This can result in timeout errors and possible loss of data. If timeouts occur, consider changing the connection type for some of the connections from COS to Cyclic or Polled.
To create an application that uses a DeviceNet I/O configuration, you must follow these steps:
  1. Configure the DeviceNet Scanner in
    RSNetWorx for DeviceNet
    .
    RSNetWorx
     contains the actual network configuration. Devices you create in
    FactoryTalk Linx
     are modeled after devices you created in
    RSNetWorx
     using the
    RSNetWorx
    Configuration Scanlist Tool. Refer to the
    RSNetWorx
     Help for more information.
  2. Define the I/O in the DeviceNet Scanner card using the
    FactoryTalk Linx
     interface.
    Each DeviceNet Scanner card contains a 2048-byte input table and a 2048-byte output table in its internal memory to store data.
    The I/O in the DeviceNet Scanner is defined on the
    Design (Local)
     tab on the
    FactoryTalk Linx
    Communication Setup
     editor. To define the I/O in the DeviceNet Scanner, you:
    1. Define blocks of memory, called address blocks, in the DeviceNet Scanner.
    2. Add devices to these blocks that model the devices you created in
      RSNetWorx
      . A device links an address block to a data source. There can be only one device assigned to each address block.
    3. Add aliases. Aliases associate a name with a particular set of information within the DeviceNet Scanner's I/O table.
  3. Use the <RSV>ME user interface to associate graphic controls with the alias names.
    Once the aliases have been created, they will be provided to the
    RSView
     client when it browses the
    FactoryTalk Linx
     server for its list of available data items. You can then assign them to components in your application, such as LEDs or switches.
You must copy the configuration to the
Runtime (Target)
tab before you create the runtime application (.mer) and transfer it to the target device. Verify your application configuration before creating the runtime application to ensure that the settings for the communication card do not conflict with anything else on the network (such as a duplicate MAC ID).
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