Cyclic reading of multiple variables with sumcommando
Description:
This sample shows how to read multiple variables cyclic by use of a read sumcommando.
 | Transporting bigger data packets Generally, HTTP-traffic is more efficient by transporting bigger data packets instead of many small packets. Therefore please use ADS sum commandos to collect your data. |
ToDo:
- Download the TcAdsJavaScript.js_Sample01.zip
- Start the PLC project
- Copy the default.htm and TcAdsWebService.js to your configured virtual directory
- Adjust NETID, PORT and SERVICE_URL if you use the TcAdsWebservice of a remote pc
<!DOCTYPE html>
<html>
<head>
<title>TcAdsWebService.js Sample01</title>
<script type="text/javascript" src="TcAdsWebService.js"></script>
<script type="text/javascript">
(function () {
var NETID = ""; // Empty string for local machine;
var PORT = "801"; // TC2 PLC Runtime = 801, TC3 PLC Runtime = 851
var SERVICE_URL = "http://localhost/TcAdsWebService/TcAdsWebService.dll"; // HTTP path to the TcAdsWebService;
var client = new TcAdsWebService.Client(SERVICE_URL, null, null);
var general_timeout = 500;
var readLoopID = null;
var readLoopDelay = 500;
var readSymbolValuesData = null;
// Array of symbol names to read;
var handlesVarNames = [
"MAIN.byteValue",
"MAIN.wordValue",
"MAIN.dwordValue",
"MAIN.sintValue",
"MAIN.intValue",
"MAIN.dintValue",
"MAIN.realValue",
"MAIN.lrealValue"
];
// Occurs if the window has loaded;
window.onload = (function () {
// Create sumcommando for reading twincat symbol handles by symbol name;
var handleswriter = new TcAdsWebService.DataWriter();
// Write general information for each symbol handle to the TcAdsWebService.DataWriter object;
for (var i = 0; i < handlesVarNames.length; i++) {
handleswriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolHandleByName);
handleswriter.writeDINT(0);
handleswriter.writeDINT(4); // Expected size; A handle has a size of 4 byte;
handleswriter.writeDINT(handlesVarNames[i].length); // The length of the symbol name string;
}
// Write symbol names after the general information to the TcAdsWebService.DataWriter object;
for (var i = 0; i < handlesVarNames.length; i++) {
handleswriter.writeString(handlesVarNames[i]);
}
// Send the list-read-write command to the TcAdsWebService by use of the readwrite function of the TcAdsWebService.Client object;
client.readwrite(
NETID,
PORT,
0xF082, // IndexGroup = ADS list-read-write command; Used to request handles for twincat symbols;
handlesVarNames.length, // IndexOffset = Count of requested symbol handles;
(handlesVarNames.length * 4) + (handlesVarNames.length * 8), // Length of requested data + 4 byte errorcode and 4 byte length per twincat symbol;
handleswriter.getBase64EncodedData(),
RequestHandlesCallback,
null,
general_timeout,
RequestHandlesTimeoutCallback,
true);
});
// Occurs if the readwrite for the sumcommando has finished;
var RequestHandlesCallback = (function (e, s) {
if (e && e.isBusy) {
// HANDLE PROGRESS TASKS HERE;
var message = "Requesting handles...";
td_byteValue.innerHTML = message;
td_wordValue.innerHTML = message;
td_dwordValue.innerHTML = message;
td_sintValue.innerHTML = message;
td_intValue.innerHTML = message;
td_dintValue.innerHTML = message;
td_realValue.innerHTML = message;
td_lrealValue.innerHTML = message;
// Exit callback function because request is still busy;
return;
}
if (e && !e.hasError) {
// Get TcAdsWebService.DataReader object from TcAdsWebService.Response object;
var reader = e.reader;
// Read error code and length for each handle;
for (var i = 0; i < handlesVarNames.length; i++) {
var err = reader.readDWORD();
var len = reader.readDWORD();
if (err != 0) {
div_log.innerHTML = "Handle error!";
return;
}
}
// Read handles from TcAdsWebService.DataReader object;
var hByteValue = reader.readDWORD();
var hWordValue = reader.readDWORD();
var hDwordValue = reader.readDWORD();
var hSintValue = reader.readDWORD();
var hIntValue = reader.readDWORD();
var hDintValue = reader.readDWORD();
var hRealValue = reader.readDWORD();
var hLrealValue = reader.readDWORD();
// Create sum commando to read symbol values based on the handle
var readSymbolValuesWriter = new TcAdsWebService.DataWriter();
// "MAIN.byteValue" // BYTE
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hByteValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(1); // size to read
// "MAIN.wordValue" // WORD
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hWordValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(2); // size to read
// "MAIN.dwordValue" // DWORD
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hDwordValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(4); // size to read
// "MAIN.sintValue" // SINT
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hSintValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(1); // size to read
// "MAIN.intValue" // INT
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hIntValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(2); // size to read
// "MAIN.dintValue" // DINT
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hDintValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(4); // size to read
// "MAIN.realValue" // REAL
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hRealValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(4); // size to read
// "MAIN.lrealValue" // LREAL
readSymbolValuesWriter.writeDINT(TcAdsWebService.TcAdsReservedIndexGroups.SymbolValueByHandle); // IndexGroup
readSymbolValuesWriter.writeDINT(hLrealValue); // IndexOffset = The target handle
readSymbolValuesWriter.writeDINT(8); // size to read
// Get Base64 encoded data from TcAdsWebService.DataWriter;
readSymbolValuesData = readSymbolValuesWriter.getBase64EncodedData();
// Start cyclic reading of symbol values;
readLoopID = window.setInterval(ReadLoop, readLoopDelay);
} else {
if (e.error.getTypeString() == "TcAdsWebService.ResquestError") {
// HANDLE TcAdsWebService.ResquestError HERE;
div_log.innerHTML = "Error: StatusText = " + e.error.statusText + " Status: " + e.error.status;
}
else if (e.error.getTypeString() == "TcAdsWebService.Error") {
// HANDLE TcAdsWebService.Error HERE;
div_log.innerHTML = "Error: ErrorMessage = " + e.error.errorMessage + " ErrorCode: " + e.error.errorCode;
}
}
});
// Occurs if the readwrite for the sumcommando to request symbol handles runs into timeout;
var RequestHandlesTimeoutCallback = (function () {
// HANDLE TIMEOUT HERE;
div_log.innerHTML = "Requuest handles timeout!";
});
// Interval callback for cyclic reading;
var ReadLoop = (function () {
// Send the read-read-write command to the TcAdsWebService by use of the readwrite function of the TcAdsWebService.Client object;
client.readwrite(
NETID,
PORT,
0xF080, // 0xF080 = Read command;
8, // IndexOffset = Variables count;
26 + (8 * 4), // Length of requested data + 4 byte errorcode per variable;
readSymbolValuesData,
ReadCallback,
null,
general_timeout,
ReadTimeoutCallback,
true);
});
// Occurs if the read-read-write command has finished;
var ReadCallback = (function (e, s) {
if (e && e.isBusy) {
// HANDLE PROGRESS TASKS HERE;
// Exit callback function because request is still busy;
return;
}
if (e && !e.hasError) {
var reader = e.reader;
// Read error codes from begin of TcAdsWebService.DataReader object;
for (var i = 0; i < handlesVarNames.length; i++) {
var err = reader.readDWORD();
if (err != 0) {
div_log.innerHTML = "Symbol error!";
return;
}
}
// "MAIN.byteValue" // BYTE
var byteValue = reader.readBYTE();
// "MAIN.wordValue" // WORD
var wordValue = reader.readWORD();
// "MAIN.dwordValue" // DWORD
var dwordValue = reader.readDWORD();
// "MAIN.sintValue" // SINT
var sintValue = reader.readSINT();
// "MAIN.intValue" // INT
var intValue = reader.readINT();
// "MAIN.dintValue" // DINT
var dintValue = reader.readDINT();
// "MAIN.realValue" // REAL
var realValue = reader.readREAL();
// "MAIN.lrealValue" // LREAL
var lrealValue = reader.readLREAL();
// Write data to the user interface;
td_byteValue.innerHTML = byteValue;
td_wordValue.innerHTML = wordValue;
td_dwordValue.innerHTML = dwordValue;
td_sintValue.innerHTML = sintValue;
td_intValue.innerHTML = intValue;
td_dintValue.innerHTML = dintValue;
td_realValue.innerHTML = realValue;
td_lrealValue.innerHTML = lrealValue;
} else {
if (e.error.getTypeString() == "TcAdsWebService.ResquestError") {
// HANDLE TcAdsWebService.ResquestError HERE;
div_log.innerHTML = "Error: StatusText = " + e.error.statusText + " Status: " + e.error.status;
}
else if (e.error.getTypeString() == "TcAdsWebService.Error") {
// HANDLE TcAdsWebService.Error HERE;
div_log.innerHTML = "Error: ErrorMessage = " + e.error.errorMessage + " ErrorCode: " + e.error.errorCode;
}
}
});
// Occurs if the read-read-write command runs into timeout;
var ReadTimeoutCallback = (function () {
// HANDLE TIMEOUT HERE;
div_log.innerHTML = "Read timeout!";
});
})();
</script>
</head>
<body>
<h1>TcAdsWebService.js Sample01</h1>
<h2>Cyclic reading of multiple variables with sumcommando!</h2>
<table>
<tr>
<td>MAIN.byteValue:</td>
<td id="td_byteValue"></td>
</tr>
<tr>
<td>MAIN.wordValue:</td>
<td id="td_wordValue"></td>
</tr>
<tr>
<td>MAIN.dwordValue:</td>
<td id="td_dwordValue"></td>
</tr>
<tr>
<td>MAIN.sintValue:</td>
<td id="td_sintValue"></td>
</tr>
<tr>
<td>MAIN.intValue:</td>
<td id="td_intValue"></td>
</tr>
<tr>
<td>MAIN.dintValue:</td>
<td id="td_dintValue"></td>
</tr>
<tr>
<td>MAIN.realValue:</td>
<td id="td_realValue"></td>
</tr>
<tr>
<td>MAIN.lrealValue:</td>
<td id="td_lrealValue"></td>
</tr>
</table>
<div id="div_log"></div>
</body>
</html>