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AN-X-AMXCAPT
January 2008
For I/O updates the destination is 255 (broadcast) since all drops see updates to and from
all other drops.
Example: The following equation selects frames with destination 255.
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Dst = 255
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Frame Control, Ctl
The second byte of the frame is the frame control, Ctl, which identifies the type of frame.
Possible values are:
Value
Symbolic name
Description
0
CTL_INIT_REQ
Init request
1
CTL_INIT_RSP
Init response
2
CTL_TOKPASS
Token pass
3
CTL_ACK
Acknowledge
4
CTL_TOKRET
Token return
5
CTL_UPDTOSLV
I/O update to slave drop
6
CTL_UPDTOMAS
I/O update to master
7
CTL_MSG
Directed message
The symbolic names can be used in the equation.
Mask off the upper bits of the CTL byte before using them in comparisons.
Example: The following equation selects frames that consist of updates to slaves or to
the master.
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((CTL&0x0F)=CTL_UPDTOSLV) OR ((CTL&0x0F)=CTL_UPDTOMAS)
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Frame Drop
On I/O updates to or from the master, the third byte in the message is the frame drop. On
updates from the master, the frame drop is the drop being updated with output data. On
updates to the master, the frame drop is the drop sending the input data.
Example: The following equation selects frames that are I/O updates from drop 2 to the
master
