Omron CX-Supervisor, User Manual

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DDE Appendix F Obsolete Features
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F.3.2 System Points
The following System Points are obsolete and are no longer updated. Scripts
and expressions will currently still compile, but their value at Runtime will
always be 0.
F.4 DDE
CX-Supervisor supports Dynamic Data Exchange (DDE), which is a method of
communication between Windows programs. DDE uses messages to
exchange data between applications and a protocol to synchronise the
passing of data. DDE applications fall into four categories client, server, client/
server and monitor. A client application requests data or services from a server
application. A server application responds to a client applications requests for
data or services. Monitor applications can intercept DDE messages but cannot
act on them, they are therefore useful for debugging purposes. CX-Supervisor
is a client/server application, which is both a client application and a server
application, thus requesting and providing information.
All CX-Supervisor DDE data transfers are carried out on points and are
asynchronous transfers. There are two types of DDE points that can be
created, namely 'DDE Client Points' and 'DDE Server Points'.
With 'DDE Client Points' all data transfers or conversations are initiated by CX-
Supervisor either sending data to or requesting data from external DDE Server
Application(s). For example, a CX-Supervisor point could be linked to update a
cell on a Microsoft Excel worksheet.
With 'DDE Server Points' all data transfers are initiated by external DDE Client
Application(s) either requesting or sending point values. For example, a value
could be entered into a cell in Microsoft Excel which would update a CX-
Supervisor point.
F.4.1 DDE Client Points
A DDE client point sends data to or requests data from an external server
application. This chapter explains how to create points that make use of the
CX-Supervisor DDE Client capabilities. In order for data to be transferred
between a point and a server application the point must uniquely identify the
application and the data that is to be used in the transfer. DDE applications
use a three-tiered identification system to distinguish themselves from other
DDE applications. An application name is at the top of the hierarchy, the
application name refers to a server application e.g. "EXCEL". A topic name
further defines a server application e.g. for Microsoft Excel the topic would
define the worksheet to be used e.g. "SHEET1.XLS", a server can support one
or more topics. Finally each topic can have one or more item names, which
uniquely identifies a data item within a topic, i.e. "R1C1" or a cell name
reference identifies a single cell within a Microsoft Excel worksheet.
Example
A DDE Client point named "DDE1" that connects to Microsoft Excel,
worksheet - "Sheet1.xls" and cell "R1C1", is created.
1, 2, 3… 1. Select the Add Point button from the Point Editor toolbar. The Add Point
dialog box opens.
$GDIResources Integer 0-100 Percentage of GDI resources free.
$SystemResources Integer 0-100 Percentage of system resources free.
$UserResources Integer 0-100 Percentage of user resources free.