Allen-Bradley 1444-TSCX02-02RB User Manual page 474

Appendix A CIP Objects
474
Normal CM Record Request - Recommendations for Network Side Implementation
The data is returned in multiple packets as an array of records of size
RecordSize and can be a significant amount of data depending on the extent of
the data requested. The recommended way to handle this data transfer is to
store the payload to a file for later retrieval.
It is recommended to store the first packet request and response packet to the
file. Thereafter, store the record array payload that is contained within each
subsequent packet. If this procedure is followed, the packet arrangement
within the file is as follows:
• RecordRequest Packet
• RecordResponse Packet (with first packet payload at the end)
– Second Response Packet payload
– Subsequent Response Packet payloads
• Last Response Packet payload
Instigate further sessions to retrieve data from any other required buffers or
channels.
Complete these steps to retrieve any record from the file.
1. Open the file.
2. Read a record with size of Normal CM Record Request from the head of
the file.
3. Access the BufferSelect variable to determine the type of record the file
holds.
4. Read a record with size Normal CM Record Response from the file
pointer.
5. Access the RecordSize variable to determine the size of the record.
6. Start at the address of the first Record in the Data Array in the first
Normal CM Record Response. Index to any record by using the
RecordSize to seek to the correct point in the file.
7. Read out the record of size, RecordSize.
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018