Indirect Tag Binding in SQL Query

Archived Topics
1

Hi,

I am trying to get list of Machines from database table, and its Current Event (‘RUN’ or ‘STOP’) from SQL Tags in a Table for Summary View. I tried with code like below and in vain:

SELECT MachineId, {[IADemo]MachineStatus/123/Event} -- Instead of 123, I want to use MachineId Column FROM MachineList ;
Is it possible to do like this or Is there any other Better way to the show the Summary View in table or other components.

Regards
Sasi Kumar Kallepalli

2

No that wont work.

Try this

SELECT MachineId, NULL as "Event" FROM MachineList

In the property change event for the table, try this in FactoryPMI

[code]def runLater(event=event):
import fpmi

if event.propertyName == 'data':
	newData = event.source.data
	for row in range(data.rowcount):
		machineId = newData.getValueAt(row, "MachineId")
		value = fpmi.tag.getTagValue("[IADemo]MachineStatus/%s/Event"%machineId)
		newData = fpmi.dataset.setValue(newData,row,"Event",value)

	event.source.data = newData

fpmi.system.invokeAsynchronous(runLater)
[/code]

In Ignition, the code needs to be modified a bit (if you want to use the actual function, not the alias)

[code]def runLater(event=event):
import system

if event.propertyName == 'data':
	newData = event.source.data
	for row in range(data.rowcount):
		machineId = newData.getValueAt(row, "MachineId")
		value = system.tag.getTagValue("[IADemo]MachineStatus/%s/Event"%machineId)
		newData = system.dataset.setValue(newData,row,"Event",value)

	event.source.data = newData

system.util.invokeAsynchronous(runLater)
[/code]

Now, this assumes the property that changed is called data, which should be true if you are using a table. If you have made a dynamic property, change the references to the new property.

3

Thank you Kyle.

Regards
Sasi Kumar Kallepalli

4

Did it work?

5

I got the values from the Real time Tag. However, I am facing new challenge

Traceback (innermost last):
  File "<event:propertyChange>", line 16, in runLater
java.util.ConcurrentModificationException

in running fpmi.system.invokeAsynchronous function.

Regards
Sasi Kallepalli

6

You should wrap the callback into the windowing system in a call that puts it on the EDT (event dispatch thread). The reasons are fairly technical. Here is the relevant code:

[code]def runLater(event=event):
import system

if event.propertyName == ‘data’:
newData = event.source.data
for row in range(data.rowcount):
machineId = newData.getValueAt(row, “MachineId”)
value = system.tag.getTagValue("[IADemo]MachineStatus/%s/Event"%machineId)
newData = system.dataset.setValue(newData,row,“Event”,value)

  def callback(event=event, newData=newData):
     event.source.data = newData
  system.util.invokeLater(callback)

system.util.invokeAsynchronous(runLater)[/code]

7

I like technical… care to share?

8

Well I’m only guessing because the poster did not provide the entire stack trace to the ConcurrentModificationException, but …

The Vision module is based on the Java Swing windowing toolkit which by design is single-threaded. That means that you should only ever modify visual elements from within the Event Dispatch Thread (a.k.a. EDT). So, when you call a function through [tt]system.util.invokeAsynchronous[/tt], it will be run in a background thread, i.e. not the EDT. So if your background function is going to interact with some visual elements (like setting the dataset of a table), you need to make sure that happens back on the EDT. This is what [tt]system.util.invokeLater[/tt] does, as defined in the User Manual.