Labview cannot get serial port response

[knakamura]

Hi everyone

I have to communicate to a serial port device, and have got it work correctly in Teraterm through COM4 port

Then I have the device displayed correctly in NI-MAX, and I'm be able to send and received through COM4 port as in the sample "Simple Serial.vi"

The problem is, I got the "bytes read" number correctly, but the response itself is empty.

Can anyone have any suggest?

Response is correctly display in Teraterm

I use the Simple Serial sample and enter the same command as in Teraterm, but the response is incorrect, but the bytes read is correct

[GerdW]

Hi knakamura,

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@knakamura wrote:

I have to communicate to a serial port device, and have got it work correctly in Teraterm through COM4 port

Then I have the device displayed correctly in NI-MAX, and I'm be able to send and received through COM4 port as in the sample "Simple Serial.vi"

The problem is, I got the "bytes read" number correctly, but the response itself is empty.

Can anyone have any suggest?

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The response string is not empty, there is atleast one char…

Switch that string indicator to "\-code" displaymode (or "hex") to see what you received.

Which command do you send to your device? Can you attach the communication manual of that device?

[knakamura]

Hi GerdW

Thank you for your reply

I've already turned to "\-code" display mode and send this command line

/\r\n

(The command itself is "/")

I don't have the manual in English, just the Japanese instruction.

But I'm sure that the command is correct, because it runs correctly in Teraterm

[rolfk]

You didn't send /\r\n but /¥r¥n

That's very different. There is no single codepage that would mix up those characters somehow since the \ character is in the lower 127 characters of the ASCII table that all codepages display they same.

[dkfire · Accepted solution]

You also get at multi line response from your device. 

You need to read all the lines. VISA read will, as default, stop the reading when it sees a received \n.   

[knakamura]

Thank you dkfire

I managed to read correctly the response.

The solution is repeating the VISA Read command through all the lines of the response.

Thank you very much, this helped me a lot.