Dde Links; Introduction; Dde Link Naming Conventions; Netdde Link Naming Conventions - Bosch DCN Manual

External Interface Manual
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DDE links

2.1

Introduction

The DCN Video Display application provides DDE (Dynamic Data Exchange) links. Through these links
external programs that have DDE client capability can access information regarding the congress. The DDE
server implemented in the Video Display application is a so-called "hot" DDE server. This means that the
server refreshes the DDE links whenever there is new data available. The DDE client does not need to ask for
an update. The DDE links are also made available as NETDDE links so other PCs connected to the DCN PC
through a MS-Windows for Workgroups compatible network can access the information too. Some DCN DDE
links can transmit large amounts of data. A DDE client that wants to access DCN DDE links must be able to
deal with DDE datablocks up to 64 kilobyte in size. The VD application must be started by the user before the
DDE links can be used.
2.1.1

DDE link naming conventions

A DDE link name consists of 3 parts:
1. The service name: This is the name used to address the DDE server. For DCN this name will
always be "DCN".
2. The topic name: This name identifies the class of data that must be transported across the DDE
link. For DCN links the topic indicates which DCN application shall provide the data.
3. The data-item name: Topics may have more than one data-item at their disposal. This name
identifies which data-item must be sent through the link.
Example: To query the voting number
Service:
Topic:
Data-item:
DDE link:
2.1.2

NETDDE link naming conventions

NETDDE link names are derived from the normal DDE link name in the following manner:
1. The service name is replaced by "\\<servername>\NDDE$". <Servername> is the network name of
the PC on which the Video application is running. (This name is determined by the Network applet
in the Windows Control Panel.)
2. The topic name is replaced by "DCN_<topic>$". <Topic> is the same topic name for the link as
used for regular DDE.
3. The data-item name is the same as for regular DDE.
Example: The same link is described as in the example above, this time provided by a PC that has
the network name "VIDEO_SERVER".
Service:
Topic:
Data-item:
NETDDE link:
The NETDDE part in the previous example is given in MS-Excel syntax. Other DDE client applications might
require a slightly different syntax especially for the | and ! characters and the quotes that separate the
different parts of the link-name. Refer to the documentation of your DDE client application for the exact syntax
required by your application.
2.2

DDE link specifications

The following section specifies, for each available DDE link, the name and its purpose, the layout of the data
and the requirements that must be met to make the link available.
Note: If a link is available but does not have any data to transmit, each link will send an empty update.
Empty updates consist of empty strings for string parts and/or 0 (zero) values for numerical parts.
Note: Because commas are used as a separator in DDE links that transmit data consisting of several
parts, undefined behaviour may occur if any string part transmitted through such a DDE link contains
commas.
Bosch Security Systems B.V. | 2004 April | External Interface Manual
"DCN"
"VOTING"
"NUM"
"DCN|VOTING!NUM"
"\\VIDEO_SERVER\NDDE$"
"DCN_VOTING$"
"NUM"
"\\'VIDEO_SERVER\NDDE$'|'DCN_VOTING$'!NUM"
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