Allen-Bradley 1444-TSCX02-02RB User Manual page 484

Appendix A CIP Objects
Table 230 - 0x4C Advanced CM Data Record Request
Byte Offset Within Structure Member
Structure
0 Buffer Select
2 RequestedCount
4 SessionInstance
5 ChannelSelect
6 SpecialRequest
7 Pad
8 PacketCountDown
12 Advanced Session Instance
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To retrieve synchronized data, the following approach is used:
• An 0x4B service is sent with Sync Data Control set to zero (any of the
modules)
• The module replies with Sync Data Control set to a specific value (a
particular tacho event number)
• Send an 0x4B service to the remaining modules with the specific Sync
Data Control value that was received from the first request
• Request the data itself with 0x4C services to all modules (see next
section)
* Synchronization can be applied using either one of the two possible TSCX
tacho signals but the associated Advanced CM tacho source setting on each of
the channels/modules must reflect the same tacho signal.
An eDeniedRequestAlreadyInProgress status indicates that an earlier request is
in progress and the data from that request has yet to be collected.
0x4C Advanced CM Data Record Request
This request is sent after the Advance CM data request has returned an
anticipated processing time and that time has elapsed. If the request is made
before the data is ready, a resource not available status code is returned. This
can be used as a polling method if a timer is not used. When the data is ready,
the data portion of the message contains the data, the other fields are also
populated as defined, and the status code indicates success.
The instance and attribute can be set to 1, but they are ignored.
Data Type Description
INT Specify the buffer to retrieve the data from: eFFT (2), eTWF (3), or eTACHO (4).The
BufferSelect does not change during a session.
INT Set RequestedCount = 1
The Requested Count does not change during a session.
USINT Functionality replaced by Advanced Session Instance.
BYTE Four bits indicating the source channel. The ChannelSelect does not change during a
session.
BYTE See Table 231 on page 485
BYTE Used to align data to a 32 bit boundary.
DWORD The PacketCountDown is initially specified as 0, but on subsequent calls the
PacketCountDown returned in the CM Record Response must be passed here.
UINT The Advanced Session Instance that is returned from the 0x4B Advanced CM Data request is
included here.
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018