Appendix A: Data Transactions
34 (70)
The live list is always accessible to the PLC on the EtherNet/IP network using acyclic parameter
access. By default, the live list is also mapped as the first eight bytes after the status word (if
enabled) to the cyclic process data in the direction from the linking device to the PLC. It is
possible to enable/disable the process data mapping of the live list. See .... "EtherNet/IP (Adapter
Interface)".
If both the status word and live list are enabled, then the status word is mapped to byte 0–1 and
the live list is mapped to byte 2–9.
If the status word is disabled and the live list is enabled, then the live list is mapped to byte 0-7.
All transactions and their positions in the live list are also visible in the Transaction Monitor in
the configuration interface.
The live list consists of a bit array with 64 elements, where each bit corresponds to a transaction
on the Modbus-TCP network:
Byte 7
Byte 6-1
Byte 0
Bit 63
Bit 62-56
Bit 55-8
Bit 7
Bit 6 - 2
Bit 1
Bit 0
Status of
transaction no
63
Status of
transaction no
62-56
...
Status of
transaction no
7
Status of
transaction no
6 - 2
Status of
transaction no
1
Status of
transaction no
0
•
Bit set to 1
Transaction successful.
•
Bit set to 0
Transaction not successful.
The reason for the unsuccessful transaction can be found on the corresponding index in the transaction
status list.
The order of the transactions in the live list conforms to the order in which they are stored in the
Modbus Server list.
A.4.1
Example
Consider the follow configuration:
•
Server 1 : a total of 2 transactions
•
Server 2 : a total of 3 transactions
•
Server 3 : a total of 1 transaction
This scenario will produce the following live list when the transactions are successful:
Bit 63
Bit 62 - 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
-
-
Server 3,
transaction
1
Server 2,
transaction
3
Server 2,
transaction
2
Server 2,
transaction
1
Server 1,
transac-
tion 2
Server 1, transaction 1
0
0
1
1
1
1
1
1
A.5
Transaction Status List
The transaction status list holds information about the transactions between the Modbus-TCP
servers and the linking device, from the perspective of the linking device in the role as Modbus-
TCP client.
Linking Device User Manual
scm-1202–181 2.0 en-US
Summary of Contents for Anybus HMS-EN2MB-R
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