Synchronous Vs. Asynchronous Method Calls - Keysight N437 Series Programmer's Manual

Synchronous vs. Asynchronous Method Calls

Keysight N437x Series Lightwave Component Analyzer, Programmer's Guide
A traditional remote control application consists of a list of actions that you
send to the instrument, expecting it to execute them in that order and to
tell you when it is done. This makes programming easy - you can do your
whole measurement in a single function or sub-routine.
In this approach you send the actions to the instrument in synchronous
mode. This means that an action you send to the instrument blocks the
program flow of the calling thread until it finishes. The advantage is that
your program structure is very simple. The drawback is that you have to
wait for the instrument to finish the action. For example this could lead to
an unresponsive user interface.
This can be solved using multi threading. Run the measurement sequence
in a new thread while the main thread handles other things like running
the user interface.
A third possibility is to call potentially time consuming actions
asynchronously. The LCA Remote Client lets you call some commands in
asynchronous mode. This means that the call returns immediately, even
before the action on the instrument has finished execution.
In such cases you need an additional method to determine, when an action
finishes. The LCA Remote Client offers two different methods to
accomplish this.
• The first is the property OperationComplete().
This property value is True, when the last asynchronously called
operation on the LCA has finished execution.
Otherwise the property value is False.
• The other method is named WaitForOPC(). This method blocks program
execution on the calling thread until the operation on the instrument
finishes.
Here are two short examples in VB.NET syntax, showing the usage of
asynchronous calls:
Remote Operation 1
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