netpower ddeserver product sheet

related information

catalog number info


users manual

before you begin
chapter 1
(overview)
chapter 2
(getting started)
chapter 3
(using ddeserver)
appendix a
(powernet and dde)

overview

dde is microsoft windows' dynamic data exchange, which is a communications protocol supported within the microsoft windows operating environment that allows cooperating windows applications to share information. dde involves a client-server relationship between two concurrently running applications. dde server in powernet acts as a dde server to applications such as microsoft excel and enhanced graphics.

to obtain data from another application, a client program opens a communication channel to a server application by specifying three thrings:

server application name. the name of the aplication that has access to the data element.

topic name. the application-specific subgroup of a data element.

specific item. a specific data element within a topic. item names are predefined and device-dependent.

with powernet, the server application name is impacc, the topic name is the node name of a particular deviceserver, and the item name is a specific device and its associated device attribute.

when an application sets up a lind to another dde program, it requests the dde server application to advise the client whenever specific data changes. these data links remain active until either the client or server program terminates the common link. this process is a very efficient means of exchanging data, because once the link is established, no communication occurs until the specified data value changes. dde is also used with enhanced graphics applications to communicate with powernet applications.

the dde server provides real-time, power monitoring data in microsoft standard dde format. hmi programs, such as cutler-hammer's netpower integrator, wonderware intouch, and others that offer dde interfaces into their software. this dde server does not require or recommend use of netpower dde for transporting information across a network. user security and access control commands are still controlled through powernet security. dde values provide validity bits ensuring data is valid and the netowrk connection is intact. one dde server is required for each dde client.

click the ddeserver icon for a snapshot of the ddeserver dialog box.

note that the above screen displays only those tags that are currently being accessed by dde. also provided is status for each tag. this dialog box can be quite useful when troubleshooting your dde application.