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When using the COM4 virtual com port on an RT system:


1. Can I send data to the RT via this port?

2. Is this port for viewing only?


I can see the bootup data displayed so I know I am talking from the RT.



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Message 1 of 4

Hi Carmine,


Are you using NI Hypervisor?  If so, then yes, you can use this virtual COM port.  Please refer to the following linked KnowledgeBase article, continued under the “Booting Process” section: http://digital.ni.com/public.nsf/allkb/5D00427FFBFE8F17862575D700713538?OpenDocument#q4


If not, then I am unsure what you are referring to.  Could you please provide some more details?



Ryan C.
Applications Engineer
National Instruments
Message 2 of 4

Yes I am using Hypervisor.


When the RT boots I can see the message come up that it is booting and has successfully booted.


BUT, it does not appear that I can interact with it. 


No prompt. Is this to be expected?


Is it just a status screen?




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Message 3 of 4
Accepted by CarmineS

Hi Carmine,


Yes, this is to be expected. The virtual COM port allows you to also receive debug strings from the real-time system as well. You can use the 'RT Debug String.vi' to write messages to the virtual COM interface.


The reason that you cannot provide an input to this console is because the underlying real-time OS (Pharlap in this case), doesn't have input capability for it's serial driver, and it so happens that the virtual COM interface is owned by the Pharlap kernel. To summarize, Pharlap based real-time systems never try to read any input from serial interfaces to the console. 


Overall, you can use the virtual COM interface for status updates from the real-time side, and may find it especially useful for debugging your application (if the need arises).


One caveat to note about the 'RT Debug String.vi' is that it does not flush until it encounters a new line or until it's buffer is filled. What this means is that if you want a status to appear on the virtual console every loop iteration, you'll want to concatenate a newline character to the string input to the RT Debug String VI. Otherwise, you will see nothing for many iterations, followed by a large output to the virtual console (after the buffer fills).

Sanjay C.
Embedded Software Product Manager| National Instruments
Message 4 of 4