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Please use our Code Center to obtain source-code and example projects/solutions:
http://codecenter.softwaretoolbox.com
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  Writing to Tags using the OPC Web Client ActiveX Controls
Quick links within this page:
Objective
Writing to a single Tag
In order for our web-page to do anything, we now need to add some scripting that will:
- respond to the button being clicked
- perform the tag write request
- display some message to indicate a success or failure
Our click-event handler will instantiate the OPC Web Client, make the call to read the value and then display it in the textbox. Here goes:
 VBSCRIPT
<html>
<head>
<title>OPC Web Client Example, Single Tag Read Within Internet Explorer</title>
</head>
<body>
<p>Enter a number to write here
<input type="text" name="T1" size="20">
<input type="button" value="Button" name="B3">
</p>
</body>
<script language="vbscript">
sub b3_onClick
set opcwebclient = CreateObject("OPCLabs.EasyDA3.0")
opcwebclient.WriteItemValue "", "OPCLabs.KitServer.2",_
"Simulation.Register_I4", Cint(t1.value)
if Err.Number = 0 then
msgbox "Successfully wrote to tag!"
else
msgbox "An error occurred: " & Err.Number
end if
end sub
</script>
</html>
Simply place the above text under the "</body>" HTML tag and then save your HTML page. Now open that web-page directly from Internet Explorer and then click on the button.
JAVASCRIPT
<html>
<head>
<title>OPC Web Client Example, Single Tag Read Within Internet Explorer</title>
</head>
<body>
<p>
<input type="text" name="T1" size="20">
<input type="button" value="Button" name="B3" onClick="doWrite();">
</p>
</body>
<script language="javascript">
function doWrite()
{
try
{
var opcWebClient = new ActiveXObject("
OPCLabs.EasyDA3.0");
opcWebClient.WriteItemValue("", "OPCLabs.KitServer.2
", "Simulation.Register_I4", document.all.T1.value);
alert("Success");
}
catch(e)
{
alert(e)
}
} </script>
</html>
With the above modification set, and with the Javascript code present, you can now save this web-page and load it directly into the web-browser.
Writing to Multiple Tags
VBSCRIPT
<html>
<head>
<title>OPC Web Client Example, Read Multiple Tags Within Internet Explorer</title>
</head>
<body>
<p>The following tags and values will be written:</p>
<ul>
<li><font color="#800000">Simulation.Register_I4 = 23456</font></li>
<li><font color="#800000">Simulation.Register_R8 = 2.34567890</font></li>
<li><font color="#800000">Simulation.Register_BSTR
= "ABC"</font></li>
</ul>
<p><input type="button" value="Write" name="B3">
</p>
<p>
<textarea rows="4" name="S1" cols="33"></textarea>
</p>
</body>
<script language="vbscript">
sub b3_onClick
Dim EasyDA
Set EasyDA = CreateObject("OPCLabs.EasyDA3.0")
Dim Results
Results = EasyDA
.WriteMultipleItemValues("", "OPCLabs.KitServer.2", _
Array("Simulation.Random", "Trends.Ramp (1 min)", "Simulation.Register_I4"), _
Array(23456, 2, 99))
dim strWriteValue
Dim I
For I = LBound(Results) To UBound(Results)
If VarType(Results(I)) <> 10 Then
strWriteValue = strWriteValue & "Element " & I & ": success"
Else
On Error Resume Next
EasyDA.RaiseError Results(I)
strWriteValue = strWriteValue & Err.Source & ": " &
Err.Description & " (0x" & _
Hex(Err.Number) & ")" & " **"
On Error Goto 0
End If
strWriteValue = strWriteValue & vbCrLf
Next
document.all.s1.value = strWriteValue
end sub
</script>
</html>
JAVASCRIPT
Feature not currently supported within Javascript due to the differences in Array handling for this development language. This feature will be made available in the next product release.
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