Presetting - Hitachi HIDIC EH-150 Applications Manual

7.2

Presetting

Before the data communication, you have to establish connection against to the other port. Here after, an
enabled connection is called as "opened connection", and a disabled connection is called as "closed
connection".
Caution
EH-ETH has 10 connections. 4 connections are only for task code communication, 6 connections are ASR
connections for message communication.
For reference
To open or close TCP/IP connection is like telephone call in our daily life.
For instance, a telephone of A is assumed as EH-ETH, telephone of B as a host computer.
In case A calls B, when B is ready to receive, B can pick up the receiver. Now both A and B are ready to speak.
On the other hand, when B is not ready to pick up the receiver, A must hang up the receiver and give up
conversation.
This is replaced to TCP/IP communication. In order EH-ETH (A) to communicate with the host computer (B),
EH-ETH (A), which is specified as active node, must request to open the connection with specifying the
destination (IP address and port number of B).
If the host computer (B) is ready to receive the request, the communication is opened and ready to be talked.
On the other hand, when the host computer (B) is not ready to open the connection, EH-ETH (A) must give up
the request after connection time out. In this case, EH-ETH (A) can not communicate with host computer.
In addition, such receiving (passive) station (B in this case) can get any requests from other than A, and can
answer (open) to all the requests. If B should open connection upon all the request, the setting "Other station"
must be "Optional". But if B should open connection upon the request from A only, this must be "Specified", and
the IP address and port number must be specified as well.
In short, a station specified as active must specify the destination. On the other hand, a station specified as
passive can be selected "specified other station" or "optional other station".
: Other station "Specified" and "Optional"
Chapter 7 Automatic Sending/Receiving function (ASR)
7-4