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  #1  
Old 02-11-2011, 12:42 PM
Hipshot Hipshot is offline
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Buffer overrrun in serial connection?

Hi Guys,
I'm running Version 6.6.2 (build 350) on my macbookpro OSX 10.6.6.
Using a keyspan USA/-19QW USB-Serial adapter, hooked up to the Console port of a Cisco 5350
The usual serial settings: 9600 n81 rts/cts (enabled) Xon/Xoff (disabled)

I copy/paste a rather hefty config in the session.
As the Cisco is chomping away at the config I see it return errors indicating that the commands I feed into it are not read correctly.

It seems to me that the Cisco is being fed lines faster than it can process. Looks very much like UART buffer overrun that happened back in the nineties when com ports had a 2 byte buffer.

Feeding the Cisco config in parts isn't really what I'm looking forward to do, a mistake is easily made.

Any suggestions please?

Hip
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  #2  
Old 02-11-2011, 01:29 PM
bgagnon bgagnon is offline
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Hello Hipshot,

You can slow the paste rate by increasing the values in the 'Send delay options' in the Terminal / Emulation / Advanced category of SecureCRT's Session Options (Line send delay).

If you need to do the same via scripting, see the Scripting Manual (section 8.3) available from our website here.
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  #3  
Old 02-11-2011, 02:15 PM
Hipshot Hipshot is offline
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Thanks

Hi Brenda,

That indeed does the trick.
I'm using conservative values: 500msec for a linefeed, 50msec per character.

Shorter delay will probably work too, but hey.. this works for me

Thanks for your support,

Hip
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  #4  
Old 02-11-2011, 03:29 PM
bgagnon bgagnon is offline
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Hi Hipshot,

Yes, some experimentation may be necessary to find the ideal value that works for a user.

Thanks for posting the feedback.
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  #5  
Old 04-21-2011, 08:39 PM
cmyers cmyers is offline
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I've fiddled with this several times. It's been a lifesaver.

Best tradeoff I've had so far is around 2-5ms character delay and 50-250ms line delay. Usually I'll go on the lower end and shift the line delay up for a few devices that are slow to process commands.

For those curious, this is what I just worked out for the character transmission times assuming 10 bits (8 data, 1 parity, 1 stop):
Code:
19,200 baud =  0.52 ms
 9,600 baud =  1.04 ms
 2,400 baud =  4.17 ms
 1,200 baud =  8.33 ms
   300 baud = 33.33 ms
So for most cases I'd wager 1-2ms character delay should be fine. Line delay just depends on how fast the device processes the commands.
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