Send unconnected messages

Unconnected messages are primarily for use in module identification, network configuration, and system debugging. Due to their unreliability and large variability of response time, unconnected messages are not recommended for applications with real-time requirements.
To send unconnected messages using the RSLinx Classic SDK, complete the following steps:
  1. Specify a path to the CIP module containing the target object.
    The application must specify the route to the target object as a sequence of path segments (or
    symbolic segments
    ), defining the CIP Port and Link Address for each link in the path. The application must use the format described in the
    Logix 5000
     Data Access Programming Manual (publication 1756-PM020). The path specification goes in a DTSA_AB_CIP_PATH structure (see Data Table Structured Address).
  2. Call DTL_CIP_MESSAGE_SEND to send the message.
    This function (in either of its forms, DTL_CIP_MESSAGE_SEND_W or DTL_CIP_MESSAGE_SEND_CB) builds the actual service request message to be routed across the network, and transmits it. The function parameters include a pointer to a buffer in which the application must have placed the IOI (
    internal object identifier
    ), or logical address, of the target object within its CIP module. This logical address must be specified in the format described in the
    Logix 5000
     Data Access Programming Manual (publication 1756-PM020).
  3. Wait for the response.
    The method by which the response is obtained varies according to which form of DTL_CIP_MESSAGE_SEND was called. See DTL_CIP_MESSAGE_SEND and DTL_SYNCHRONIZATION.
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