Desperate questios on RS232 Communication

Hallo all expert,
The attachment is a vi which is expected to write/read data to/from COM1 of my machine. For verification, I simply short circuited pin 2 and 3 of the RS232 port. However there are some questions following my experiment:
1. In the chart the label of x-axis can not be restored to be 0 to 100, it automatically increases without limits. I wish it start from 0 instead resuming a time instant;
2. In the "read string" field the display is not updated during my typing characters in "string to write", although I have enabled "Update Value while Typing";
3. The display in the chart doesn't correspond to what I have typed. Should I need more functions in order to show up the data?
My final purpose is to use this interface to communicate a pic chip which I programed to realize A/D conversion. At begin, a value is ought to be sent to the chip where the value is compared and if it is "1"f, then the conversion is initiated, and the value is read in the chart and could be also saved a excel file for documentation.
I'm wondering how to input value "1", instead string "1". I successfully type "Ctrl-A" in HyperTerminal, but have no idea which function is due to be used to realize the corresponding conversion.
Attachments:
myrs232r_r.vi ‏36 KB

There are several ways to send a hex 01 with the VISA Write, and all have been explained numerous times onn the forum. One wya is to simply right click on your string control/constant and select Hex Display. You can right click and select '\' Code Display and enter \01. You can have a numeric control and use the Byte Array to String. You can have a numeric control and use the Typecast function to convert to a string.
Your error can be due to the device not sending any data back, hence the VISA Read times out waiting for non-existant data. If you sometimes get data and are unsure of the length, you need to use VISA Bytes at Serial Port wired to the byte count input of VISA Read. This has also been discussed numerous times on the forum.
Message Edited by Dennis Knutson on 04-19-2007 06:15 AM
Attachments:
write hex to serial.PNG ‏4 KB

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Sorry I am new posting a message here and I post it before I was able to describe my problem.
I have a Kollmorgen Servostar 300 to control an AKM24F motor and I would like to send the instructions to the controller via RS232 using LabView. I think I had achieved communication from a PC to a Servostar 300 using LabView via the serial port.
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Problem with serial communication PLEASE HELP

Hello everybody !
I'd like to ask You for some feedback on my wierdo problem that I got with my program.
I have built a device that detects changes in magnetic field. It is used for detecting vehicles passing it on a highway. Generally the main components communicate with each other by RS-485 protocol, but I would like to connect the device to a PC. To do so I am using a RS-232 protocol (I have a RS485=RS232 hardware converter).
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I also thought about using VISA drivers, but I am having trouble with it as well - the damn thing just does not work.
My very bling guess is that everyting that I am expierencing is about using the communication protocol and seting it right. I am attaching both of the programs, PLEASE anyone pretty pretty help I totally ran out of ideas and knowledge and day after day I am turning it on and off on my PC and notebook hoping some miracle will occour ...
Many many thanks in advance !
Best regards
Tom
P.S. the program is very unfinished (man things are just put in), the main thing I am struggling now is getting, and setting the communication protocol right.
Attachments:
detektor_3_2.vi ‏141 KB

The biggest problem I see is in the sequence:
Write out a string.
Wait 50 mSec.
Ask how many bytes have been received.
Read that many bytes.
Can you guarantee that the data can make a round trip in 50 mSec?
You should know that the SERIAL PORT WRITE completes NOT when the data has been sent out the port, but when it has been BUFFERED for sending. In other words it returns and starts the timer BEFORE it is actually sent.
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If you can control the protocol of what gets sent back, I would change your receiving logic. I think you should check for a carriage return or some other delimiter, and not react until you get that character (or until a reasonable timeout expires).
In other words, try synchronizing the two ends. Something like:
N = Get # bytes at port
Read N bytes from port (flush any characters waiting).
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until Found or (Now > TimeLimit)
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You are also re-initializing the port (SERIAL PORT INIT) every time thru the outer loop - that's unnecessary.
Steve Bird
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Culverson.com
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Attachments:
Serial_Test_1.vi ‏45 KB

Greetings!
Serial port commucations problems can be a real joy, can't they? Have you tried communicating with your instrument with Hyperterm? Usually Hyperterm is capable of operating with almost no overhead, so you can see if there's any strange symbols being transmitted that might be holding things up. There might be an extra CR being inserted, or something like that, which will show up as heiroglyphics in Hyperterm. See if all your symbols coming back are valid. This is where I usually start.
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Hello!
I'm trying to make a simple serial port reader VI and i can't get over this:
Error -1073807253 occurred at VISA Read in communication.vi
Possible reason(s):
VISA: (Hex 0xBFFF006B) A framing error occurred during transfer.
I'm pretty shure that the device sending a data works properly and the parameteres like a boud rate, parity etc. are set correctly because I've already communicate with that device via Matlab.
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Attachments:
VI-rs232-trouble.jpg ‏106 KB

chikvadrat wrote:
The VI works well after launch. It also read first 9 character correctly, but after that it crashs.
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I have problem in communication. I have one sensor imar sensor that can be easily communicate in Hyperlink but if I send same command for example "show conf" it doesn't responses It is connected with rs232 in com port 1. it will be nice if you give me some suggestion thanking you
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Solved!
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Yeah I can't open that (needs to be 2010 or earlier - see my first post)
Is 57600 baud rate the one specified in the manual for your device? This needs to be absolutely correct for the serial communications to work properly.
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Message Edited by Michelle1892773 on 02-22-2010 02:00 PM

Something like this?
I do have to say, i don't know what is happening in the false case of yours, but if nothing happens with the 100 that is wired to the shift register, once you enter the true case, the value in the shift register will always be great than "i". You might as well do what I have done then. However, if something does happen with that number in your false case, then keep it the way you have it.
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Message Edited by for(imstuck) on 02-22-2010 04:45 PM
Message Edited by for(imstuck) on 02-22-2010 04:46 PM
CLA, LabVIEW Versions 2010-2013
Attachments:
visa.PNG ‏13 KB

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NI Software : Lookout
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Customer Information :
Raja Mahbubani
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[email protected]
Solved!
Go to Solution.

claudio.rossi wrote:
Hi at all!!
I'm new in NI forum.
I have one similar problem. My VI communicate with external device on serial port. The VI work very well, but when I create executable (.exe) file with Labview application builder (on Labview 2010) the .exe don't use serial port!!! The executable run perfectly (nothing error or warning by the application builder), but the serial data on selected COM port isn't send!!! Also on the PC where I developed the VI!!!
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I have problem with communication bethween 2 computers

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