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ProSoft Technology AN-X-AMX User Manual

Page 26

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22

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