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New Member

console showing unrecognizable characters?

cisco_3512xl_console_issue.png

3512XL, Tera Term serial console

I think BAUD is set correctly because the switch responses to commands like enable but the characters are unrecognizable...

What can be the cause of this problem?

I tried recovery mode with 9600 BAUD and the image is what I got...

The other 3512XL works fine... I don't think what has been configured on the switch tho...

Everyone's tags (2)
2 ACCEPTED SOLUTIONS

Accepted Solutions
Cisco Employee

Re: console showing unrecognizable characters?

Hello,

Please try to test these speeds: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200. Other speed values are invalid. Every time you change the speed, hit a few times to see if the switch' response becomes intelligible.

Regarding the config register: good thinking. On routers, the config register also holds the information about the console port speed. Switches, however, do not have a configuration register at all. The 0xF value you see displayed on switches is just a phony constant that can not be even changed.

Best regards,

Peter

VIP Super Bronze

console showing unrecognizable characters?

You can't set the speed to none standard values, it will reject it.

3750-Switch(config-line)#speed 9609     

Failed to change line 0's speed

3750-Switch(config-line)#speed 9600

3750-Switch(config-line)# 

So, you just have to try every single value that Peter provided you in his post.

The other thing you can try is to use a different terminal emulator like putty.  It is also free.

Overall, Putty is better than tera term.

HTH  

7 REPLIES
New Member

Re: console showing unrecognizable characters?

What I can suggest is to check the setting for the console.

bps - 2400

Databits - 8

Parity - none

Stop bits - 1

Flow Control - None.

Please confirm, if you are using the same values there ...

And do not forget to rate the post .. if it helps..

Cisco Employee

Re: console showing unrecognizable characters?

Hello Parvesh,

To my best knowledge, the correct baud (or more correctly, bit speed) setting with Cisco devices has always been 9600 bits per second, not 2400. Please correct me here if I am wrong.

To realdreams: these characters displaying on the screen actually suggest that you are using a different COM port speed than what is currently configured  on the switch. The fact that the characters seem to react to your keystrokes means that your speed is close, but still not correct.

Best regards,

Peter

New Member

Re: console showing unrecognizable characters?

Yeah the default BAUD is 9600 bps.

I incremented the BAUD and anything above 115200 gets the same result as shown, anything  below just won't show anything... I don't know how but when I set BAUD back to 115200 in Tera Term, it started displaying the characters correctly.... I am sure I tried 115200 before but it didn't work..... I don't know what exactly caused it....

On switches confreg 0xF is the default, is that correct? I was thinking confreg might be what's causing the problem. But it seems confreg on switches works differently than it does on router...

Cisco Employee

Re: console showing unrecognizable characters?

Hello,

Please try to test these speeds: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200. Other speed values are invalid. Every time you change the speed, hit a few times to see if the switch' response becomes intelligible.

Regarding the config register: good thinking. On routers, the config register also holds the information about the console port speed. Switches, however, do not have a configuration register at all. The 0xF value you see displayed on switches is just a phony constant that can not be even changed.

Best regards,

Peter

New Member

Re: console showing unrecognizable characters?

Is it possible that someone set a non standard value for console speed like 9609 (kinda typo)? Does that value get rejected with an error message?

VIP Super Bronze

console showing unrecognizable characters?

You can't set the speed to none standard values, it will reject it.

3750-Switch(config-line)#speed 9609     

Failed to change line 0's speed

3750-Switch(config-line)#speed 9600

3750-Switch(config-line)# 

So, you just have to try every single value that Peter provided you in his post.

The other thing you can try is to use a different terminal emulator like putty.  It is also free.

Overall, Putty is better than tera term.

HTH  

console showing unrecognizable characters?

hi restart switch and enter into rommon mode configue baud rate

if it still not works then we call it's showing garbage o that may lead to hardware issue also

Jawad

Jawad
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