Read data from XML file.

[stark8]

Hi,

I have a doubt about reading data from XML file. I need to read the Channel number from channel429 and also need to verify whether each channel has TX or RX or both TX and RX. 

I have attached the XML file below.

Thanks.

Here is the XML file data:

<board429 xmlns="http://www.aviftech.com/Schemas/Databus/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" dataRateModifier="MINUS_7_7_PERCENT" lowSpeedSelection="INTERMEDIATE_LOW_SPEED" sdiModeEnabled="true" xsi:schemaLocation="http://www.aviftech.com/Schemas/Databus/ file:///c:/vcprojects/owl429/documents/XML/AIT_429.xsd">

<boardIndex>0</boardIndex>
<channel429> channelNumber="1" channelSpeed="HIGH_SPEED_CHANNEL">
<Tx maxAsyncronousBufferWords="256" parityEnabled="true" startWithExternalTrigger="false">
<TxScheduledLabel transferCount="1" transferPeriod="125">
<wordBuffer depth="1" label="11">
<data23>7FFFFF</data23>
</wordBuffer>
</TxScheduledLabel>
</Tx>
<Rx>
<chronMonitor>
<simpleFilter>
<labelFilterCondition label="11"/>
</simpleFilter>
</chronMonitor>
</Rx>
</channel429>
<channel429 channelNumber="2" channelSpeed="HIGH_SPEED_CHANNEL">
<Rx>
<chronMonitor>
<simpleFilter>
<labelFilterCondition label="11"/>
</simpleFilter>
</chronMonitor>
</Rx>
</channel429>
<channel429 channelNumber="3" channelSpeed="HIGH_SPEED_CHANNEL">
<Tx maxAsyncronousBufferWords="256" parityEnabled="true" startWithExternalTrigger="false">
<TxScheduledLabel transferCount="1" transferPeriod="125">
<wordBuffer depth="1" label="11">
<data23>7FFFFF</data23>
</wordBuffer>
</TxScheduledLabel>
</Tx>
<Rx>
<chronMonitor>
<simpleFilter>
<labelFilterCondition label="11"/>
</simpleFilter>
</chronMonitor>
</Rx>
</channel429>
<channel429 channelNumber="4" channelSpeed="HIGH_SPEED_CHANNEL">
<Rx>
<chronMonitor>
<simpleFilter>
<labelFilterCondition label="11"/>
</simpleFilter>
</chronMonitor>
</Rx>
</channel429>
</board429>

[GerdW]

Hi Hemanth8,

---

@stark8 wrote:

I have a doubt about reading data from XML file.

---

Which "doubt" do you have?

What have you tried and where are you stuck?

(As XML is just a text you can always use string functions to collect all the needed information…)

[raphschru · Accepted solution]

Hi,

What is your doubt, what have you tried ?

Have you tried with the XML parser API ? Open function palette -> File I/O -> XML -> XML Parser.

This is not easy to use, but you can read/write any XML structure with it.

Attached is an example for your use case.

Regards,

Raphaël.

[stark8]

Thankyou, It really helped me to learn about fetching data from XML file.

[stark8]

Hi, 

Can you provide me more information about how the Element refnum, and node result refnum in the code code are created and how it works in the code. I'm not getting any idea about how they work.

Thankyou

[raphschru]

Hi,

XML Parser VIs all use references from the "XML Parser" class hierarchy. One of the base classes is "Node", which represents a generic node in the XML document. Subclass "Document" represents the whole file, and subclass "Element" represents any node that is a child of the document. Some methods such as "Get Attribute" are only available on Elements, not generic Nodes, which is why a type specialization is needed.

The Refnum Constant can be created with right-click option "Create Constant" from an already existing XML wire. Then right-click on the created constant -> Select XML Parser Class -> Node -> Element.

The node used to type cast here is "Coerce To Type". Go to function palette -> Numeric -> Conversion -> Coerce To Type. The use of this node for a type cast is an exception for XML Parser classes, as for other class hierarchies such as VI Server or LV Objects, you normally use "To More Specific Class" and " To More Generic Class" from the Application Control palette.

Finally, all references created must be closed when not needed anymore. Also beware of race conditions with refnums. You must not close a refnum while using it in parallel. Use error wire to ensure the order of execution of functions.

I'm putting an image of the code that we are discussing so that other people can understand:

Regards.