The scheme implementing this will be:. Very good article and impressive work! Such an approach based on chaining asynchronous tasks via callbacks bears some resemblance to the way Labview works: The assembly defines two namespaces: The constructor of each of these classes will throw an exception if the device initialization fails. Trim ; should be numericUpDown1.
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For the “receive” operation this time includes pgib the waiting for the device to be ready and the time needed to transfer the data. GPIB is a bus where the controller PC decides when each device is allowed to send data therefore the GPIB “write” and “read” operations can be interleaved, leading effectively to a parallel query of several devices at a time:.
You also can use the Resource to Find field to query each instrument for an identification ID string. Whereas the create device class with this visz is device string name, string address. Views Read Edit View history. MustInherit class from which various kinds of real devices are derived as child classes. Two delays are concerned: Unsourced material may be challenged and removed.
For asynchronous methods the only place you get access to such a variable is in the callback function, but you don’t seem to use the version with callback here this one would give null response string as explained in the manualfor the command “device1.
If your GPIB device is SCPI-compliant, the name and address gisa in the lower main window once the instrument name in the configuration tree has been clicked. This class also adds methods to set and get Visa attributes here limited to most common attribute types: If you already know your resource string, you enter it into the Resource field.
ID querying is discussed in the next fpib. This indicates that you should check for loose or disconnected cables, power disruption, or a malfunctioning instrument. SendAsync “50”,true ; The SendAsync method returns 0 which means it is working ok but when the method completes and the command is actually sent, it times out.
It serves as message termination character. Message 8 of 9.
This works quite well as I could easily obtain relatively high reading rates e. There is an example of function doing all these configuration steps in the test Form:. The SerialPort class instance members are not quite thread-safe but since in this code we never have two threads talking to the same COM port at the same time the serial interface locking can be disabled too.
This page was last edited on 14 Novemberat But maybe I’m wrong and we need something more when two NI boards are used. Then at the time we receive a response from device 1, the devices 2 and 3 might be ready too to send data therefore there is no additional performance penalty due to devices 2 and 3.
Message 4 of 9. Then the method ” WaitAsync ” can be used for synchronization between the asynchronous command queue and the main thread: Tms; try to set it to a longer value and recompile the IODevices assembly. Select a Web Site Choose a web site to get translated content where available and see local events and offers. I have tested the SerialDevice class with several devices attached via a Prolific USB-serial converter, with interface locking disabled, so far I did not detect any problems.
This whole sequence can be implemented asynchronously if the query on the second device will be called from the callback function handling the query of device 1.
Communicating with Your Instrument – MATLAB & Simulink
Pawel Wzietek Apr 3: In the left Tree-control branch Devices and Interfacesyou can search for your instrument or add a new one. If there is a problem, you no longer see your device.
Such an approach based on chaining asynchronous tasks via callbacks bears some resemblance to the way Labview works: