Example, Timing issues related to visual basic controls – Echelon LNS DDE Server User Manual

Page 84

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StatusTag

A tag containing the return value from the WWRequest
function. The value is 1 for a successful update, 0 if the
application is busy, and –1 for an error.

Application

The DDE application as a string or an InTouch tag. By
default, this is “LNSDDE” for the LNS DDE Server.

Topic

A DDE topic as a string or an InTouch tag. For network
variables, this will be an LMNV, DevNV, or NV topic as
described in Topics in Chapter 4 and in Specifying a Network

Variable earlier in this chapter.

Item

A DDE item as a string or an InTouch tag, as described in
Specifying a Network Variable earlier in this chapter.

Value

A string or an InTouch tag specifying the value to be sent to
the network variable.

8

Click OK for the two open dialogs to return to the application window.
To exit design mode and enable the button, click Runtime! in the menu
bar.

Example

StatusTag = WWPoke("LNSDDE", "LNS DDE Test.HVAC.LMNV", _

"DO- 1.LED 4.Digital", ValueTag)

Timing Issues Related to Visual Basic Controls

If you receive the DDE exception “Timeout waiting for a DDE Response” when

establishing an automatic link or making an explicit Link Request for a control,
increase the LinkTimeout property.

If you observe that your Visual Basic control does not receive expected data changes,
make certain that you have not terminated the DDE Link on the control before the

data change has arrived.

5-14

Reading and Writing Network Variables

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