Author Topic: Zmodem CRC Error  (Read 1981 times)

engkfke

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Zmodem CRC Error
« on: March 23, 2011, 11:38:16 am »
what Cause CRC Error in Zmodem and how can i avoid it?

Roman Novgorodov

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Re: Zmodem CRC Error
« Reply #1 on: March 23, 2011, 11:55:58 am »
Hello

CRC controls the data integrity of transmission. This error is possible during serial transfer of large data size or high speed.
Possible you select non correct serial port settings (baud rate, parity etc.) or quality line is not ideal.

If ZModem detects CRC error, it re-sends failed data packet. Max number of attempts is ErrorLimit property value.

Do you see this error immediately or it appears from time to time?

Roman Novgorodov
DeepSoftware.Com
« Last Edit: March 23, 2011, 12:02:13 pm by Roman Novgorodov »
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engkfke

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Re: Zmodem CRC Error
« Reply #2 on: April 12, 2011, 01:46:21 pm »
No this error appears from time to time in transfer at high speed (28800) and a large size files.
MY properties at nrCommTapi are baud rate (115200) , Flow Control is Hardware ,  RTS and DTR are enabled ,Call fail Timer =60, what is missing ??

Roman Novgorodov

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Re: Zmodem CRC Error
« Reply #3 on: April 12, 2011, 03:23:17 pm »
Hello

CRC errors are possible on big size file and high baud rate. It is normal situation for serial communication tasks.
You need increase ErrorLimit value for resend broken packets.

Also please note that there are no modem with real speed 115200. It is connection speed between modem and PC only. Real speed for phone line is 57000 no more.
Possible something wrong in settings of modem driver.

Roman Novgorodov
DeepSoftware.Com
« Last Edit: April 12, 2011, 03:25:59 pm by Roman Novgorodov »
DeepSoftware llc - The professional components for Delphi/CBuilder/.NET. The high quality custom software development.
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engkfke

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Re: Zmodem CRC Error
« Reply #4 on: April 13, 2011, 10:05:50 am »
Dear Roman,
Thank you for fast kindly response ,,

I tried to transfer Big file using the same modem on Windows terminal via zmodem protocol and i haven't any problem with it so i think there is some thing missing in my configuration.
For your information this is the first time to face this problem with nrCommTapi but also i have tested he modem in another terminals and i haven't any problem with it.
So do you have another idea about to avoid this problem ??

Thanks in advance.

Roman Novgorodov

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Re: Zmodem CRC Error
« Reply #5 on: April 17, 2011, 04:20:05 pm »
Hello

We can not reproduce trouble on our side with our hardware.
Please create a simple demo project that shows problem. And upload its sources here.

Roman Novgorodov
DeepSoftware
DeepSoftware llc - The professional components for Delphi/CBuilder/.NET. The high quality custom software development.
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