ISPSoft User Manual

Chapter 16 Network Configuration and Data Exchange
Besides, if the users do not set the parameters related to a PLC Link in the original master station
again before they designate another device as a master station, an error occurs when more than
one device sends reading/writing commands. As a result, if the users want to designate another
device as a master station, they have to make sure that the original master station does not execute
the original PLC Link.
* In addition to the conditions mentioned above, users have to prevent two devices or more than two devices from
sending reading/writing commands simultaneously in any conditions.
16.4 Constructing an Ether Link
16.4.1 Introduction of an Ether Link
An Ether Link is a network mechanism for data exchange performed through an Ethernet
connection. If there are several nodes in an Ethernet network, users can create a mechanism for
data exchange in the network, and select a start mode. If the parameters which are set are
downloaded to the PLCs in the network, the systems of the PLCs perform data exchange according
to the start mode selected when the PLCs run. The users do not have to write a redundant program.
Besides, only AH500 series CPU modules support Ether Links.
A PLC Link is a master/slave model. There is only one master station in an RS-485 network, and the
other stations which are slave stations passively receive reading/writing commands from the master
station. Compared with a PLC Link, an Ether Link adopts a safer data request mechanism. It is the
data demanding nodes in an Ethernet network that execute an Ether Link.
An Ether Link is not a master/slave model. It allows a node to send reading commands which ask
for data to other nodes. The nodes will send the data to the node after they receive the reading
commands. Owing to the fact that a node can not send writing commands to other nodes, the use of
an Ether Link is safer than the use of a PLC Link. Besides, all the nodes in an Ethernet network can
send reading commands through TCP/IP, and the system automatically manages the transmission
of packets through TCP/IP. Compared with a PLC Link, an Ether Link is more efficient.
Please refer to the example below for more information. If users want to create an Ether Link shown
below, they have to create a data exchange table for the two data request nodes AH-01 and AH-02.
(a) AH-01 reads the data in D100~D109 in AH-02, and stores the data in D0~D9 in itself.
(b) AH-02 reads the data in D200~D219 in AH-01, and stores the data in D110~D129 in itself.
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