Serial Recieve with termination character

Hi All,
I have developed a seqence fileto transmit data on the serial port and loop back to recieve the data on reciever of same port. I'm transmitting "Test
Serial" (Note: I'm not transmitting "Test\\rSerial") and recieving the data with termination character "carriage return".I'm using ASCII value 13 for the carriage return,but the recieve is not terminating on carriage return.
It seems Teststand is not able to recognize "13" or "\r" is seen as 2 character.
I'm attaching the sequence file for your perusal.It would be great if somebody can suggest me ways to make this work.
Thanks in advance.
Regards
VDC
PS: IVI serial driver need to be installed.You need to select Serial driver in device driver installation
Attachments:
SerialReadWrite_Term.seq ‏23 KB

HI,
I tried to find this dll, where is it located?
If this is using "IVI" then you could see every action in NI-Spy !
I watched you code. Another thing you could try is disabling the caching. Try Cache=0
now data shold send very time to your device by the IVI engine
Juergen
=s=i=g=n=a=t=u=r=e= Click on the Star and see what happens :-) =s=i=g=n=a=t=u=r=e=

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Attachments:
488_query.vi ‏16 KB

Generally issue with termination character.
And you are sending \ and r and not CarriageReturn.

Serial port termination character status?

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I need to read a message from a serial port and I'm having some problems. I used the advanced serial communication example and came up with the attached program. Everything works perfectly fine except for the fact that if no message is sent for 10 seconds as designed the serial read outputs an error. I know normally I can check to make sure there are bytes at the port before I do a read operation which solves this problem. However, when using the buffer to terminate the read once a termination character is provided the bytes at port property always returns 0 so I can't use this as a conditional for reading the port.
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Attachments:
serial_buffer.gif ‏19 KB
serial.vi ‏15 KB

Let me maybe give a bit more details about the application. I want to be able to get any amount of characters as a string that someone inputs in to the serial port. This will be a computer so I can expect the commands to usually be valid but I want to provide some additional redundency incase a person at a terminal is writing commands. The commands might be "measure 110" or it might be "set 23 34". So the amount of bytes being sent will depend on the command. I used 1000 as the byte count on the read just to provide as much room as possible, setting it to 100 doesn't really make a difference in this application, the same thing happens. If someone starts typing in a terminal "measure 110" (for example) but forgets to hit enter for the termination character the program will time out since the error cluster is connected to the stop button of the loop. When this happens the entire program needs to be restarted. Not really ideal.
If I disconnect the error cluster from the stop button I noticed it works perfectly fine. After 10 seconds of the terminator character not being entered the buffer clears and the loop simply restarts. What I worry about is if there is some other fatal error (such as not being able to connect to the serial device) that the program will keep running. Is this something I even need to worry about?
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Attachments:
serial_buffer.gif ‏20 KB

Termination character for serial write

Hi there,
(LabView 6.02 on Win2k)
Trying to communicate with a serial device I open a VISA-session on
COM1 and it all works fine except that I'm not able to configure a
termination character.
I've tried the as well as the VISA property
nodes. But I never get the desired termination characters (0xA or 0xD)
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What am I doing wrong?
Thanks in advance,
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finally I found out the following:
For the VISA session you have to setup (by means of property nodes)
not only and
but also set to "TermChar". Now everything
works fine :-)
Bernd-U. Seifert wrote:
> Hi there,
>
> (LabView 6.02 on Win2k)
> Trying to communicate with a serial device I open a VISA-session on COM1
> and it all works fine except that I'm not able to configure a
> termination character.
> I've tried the as well as the VISA property
> nodes. But I never get the desired termination characters (0xA or 0xD)
> sent to the port.
>
> What am I doing wrong?
>
>
> Thanks in advance,
> \Ulli.
>

Why do I get a "termination character was read" warning with VISA read and TCPIP?

I am using VISA Reads with TCPIP raw sockets without issue with NI-VISA 3.0.1 but when I moved to NI-VISA 4.4 I was getting timeout errors. The timeout errors went away when I set the termination character enable property to true (which seemed to be default in NI-VISA 3.0.1), but now I get a warning stating that the "termination character was read".
Can I disable this warning? Can I set the termination character enable to default? How can I get rid of this annoying warning?
Solved!
Go to Solution.

Hey Dagwood,
Unfortunately there isn't a way to globally change the attribute VI_ATTR_TERMCHAR_EN to VI_TRUE. I spoke with R&D about possible use of the registries and they say it's not accessible through that. To address why this change was made, the developer who made the switch isn't around anymore so I can't find his reasoning as an explanation for you. The best this for you to do in your code would be while initializing, use the VISA Property Node to make the change and until that VISA Resource is closed, this change will remain set to the value you assign. I'm sorry we cannot provide any other solution for this inconvenience. Also, if you feel this is a large burden on your programming practice you can definitely submit a product suggestion for the ability to change global default values for VISA attributes.
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How can I define more than one termination character for RS-232 interface communication?

Hi,
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Go to Solution.

That would be for the write. The poster is asking about the read. For the read you will need to write your own read routine. You will basically need to use a loop and inside the loop use the VISA Bytes at Serial Port to see if there's any bytes available. Read that many bytes, and append them to a string that you build up in a shift register. After concatenation check to see if you've got the termination characters. If so, the read is done. Fairly simple. Be sure to turn off the termination character enable in the VISA Configure.

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I'm talking to a 3rd party device over USB where I make function calls to their DLL. I send and receive Hex commands as Strings data type. I can send without problem however when I read back a string that should be Hex "FF 00 FF", I get back "FF" because LabVIEW sees 00 as a termination character so I don't get any data past the 00. Likewise if I'm supposed to read "00 FF", I get back nothing! The following KB linked below explains that LabVIEW sees 00 as a termination character. It shows where using Serial to change the termination character to something else. I don't have this option using my 3rd party USB device. Is there a way to change what LabVIEW sees as it's termination character?
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That article is talking about two things. The first has to do with the fact that in C strings are terminated using 0x00. The second part has to do with a serial port read terminating once it sees 0x00. Based on what you described, I don't believe the second part does not apply to you since you are calling a third-party DLL, so it's doing the serial port read. Is this correct? Or, are you actually doing the serial port read yourself using VISA functions? If you are just calling their DLL, then the issue has to do with the string being passed back from the DLL to LabVIEW. You're probably passing in a string datatype. You should simply change this to a byte array so you get all the values.

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Termination character

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I'm communicating with an 20 years old optical spectrum analyzer with GPIB connection using VISA.
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here is the example, i am on HP UNIX
SQL> DECLARE
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22                       );
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Hello
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SQL> ed
Wrote file afiedt.buf
1 DECLARE
2     l_text   VARCHAR2 (32767);
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Termination character enable

I am connected to hardware via an RS-232 cable and am using VISA’s to request and read information from memory addresses. When I encounter a 0x0a (hex) in memory, the VISA Read stops reading because it thinks it has read the termination character. This only happens when a 0x0a is encountered, all other characters from 0x00 to 0xff are read in correctly (provided there isn’t a 0x0a in the location).
I have set the Termination Character Enable property node to FALSE and it doesn’t seem to help (Ver 6.0.2). Any help on disabling the Termination Character would be appreciated.
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