Serial read issue

[jpparmar]

Hi, I'm trying to read data on RS422, but having issue with the reception.

The DUT sends 36bytes every 2ms and i'm trying to receive this data inside labview. the complete bunch (of 36 bytes) is sent in approx 800 microseconds.

when I'm using serial read inside while loop, the received data bytes are randomly shifted.

when i read 100 or more bunches at a time (without using while loop), then everything is received ok.

What could be the issue. Please suggest solutions.

regards,

[wiebe@CARYA]

Sound like it could be a misconfiguration of the serial port. Wrong Nr. of stop bits, or parity bit maybe?

[GerdW]

Hi jpparmar,

probably there is a problem in your code.

As you didn't attach your code/VI you need to debug it on your own…

[jpparmar]

The configuration seems to be ok i.e., data bits=8, start bit= stop bit =1, parity =nil.

Also, if the config is not ok, then the version with no while loop will also not work.

[jpparmar]

The block diagram is attached.

[GerdW · Accepted solution]

Hi jpparmar,

are you reading "binary" data from your device - or formatted ASCII?

Mabye the TermChar crushes your messages!?

Notes:

• Read the help for the VISASerialConfig function. The full help on all its inputs…
• The way you read messages need to fit to the message content. Unfortunately you don't provide any information on the message format nor the device sending them…

[jpparmar]

bd3 works fine. it receives 100 bytes and stops.

while bd1 works but byte locations are shifted.

[GerdW]

Hi jp,

bd3 works fine. it receives 100 bytes and stops.

It is working "fine" with receiving just 100 bytes even though you are requesting for 3600 bytes???

[wiebe@CARYA]

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@jpparmar wrote:

The configuration seems to be ok i.e., data bits=8, start bit= stop bit =1, parity =nil.

Also, if the config is not ok, then the version with no while loop will also not work.

---

Not per se.

If handshaking is done after a message, what is consisting a message will make a difference. I'm not sure if it can actually happen, but I wouldn't rule out the configuration.

If you are communicating binary data, the configuration of termination characters is definitely wrong.

[jpparmar]

@ GerdW

The data is binary.

I made a mistake. I am receiving 3600 bytes not 100. The version without while loop is working fine as required.