Console problem from Linux


I'm trying to get linux to talk to a Cisco 837 using the supplied blue console cable. The serial port is detected by linux and seems alright as you can see below.


0: uart:16550A port:000003F8 irq:4 tx:149 rx:121

Tx and Rx indicate that bytes are being sent/received. Now here's the thing, neither minicom nor kermit will show any output at all (i'm no guru when it comes to this but i have my settings correct as in speed, parity, stop bits etc..)

Also, the cisco shows this:

------------------------- eon#show line console 0 Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int 0 CTY - - - - - 0 163 0/0 -

Line 0, Location: "", Type: "" Length: 24 lines, Width: 80 columns Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits Status: Ready Capabilities: none Modem state: Ready Special Chars: Escape Hold Stop Start Disconnect Activation ^^x none - - none Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch 00:10:00 never none not set Idle Session Disconnect Warning never Login-sequence User Response 00:00:30 Autoselect Initial Wait not set Modem type is unknown. Session limit is not set. Time since activation: never Editing is enabled. History is enabled, history size is 20. DNS resolution in show commands is enabled Full user help is disabled Allowed input transports are none. Allowed output transports are telnet ssh. Preferred transport is telnet. No output characters are padded No special data dispatching characters


Notice the 'noise' column, and that value of 163 since that's what happens when i connect using minicom and type random stuff. Though I don't get replies, that increases the noise count, so it must be that the Cisco is discarding the packets as noise.

Does anybody know how to solve this and get it to work?


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Try "1" And I didn't see any mention of flow control... IIRC, I had to turn flow control off for my 29XX switches.

Reply to
John Oliver

Are you using an external serial adapater (DB9 to RJ45)? If so are you sure you're using one with the right pinout? Confirm that both your cable and adapter work with a known good computer. I'll send you my two minicom config files as well.

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I tried setting the stop bits to 1 and manually turning off flow control in the cisco but this had no effect. All that it records is still noise.

Btw, the default config is what I posted originally but I too believed it should be 9600 8N1. I've checked this with multiple devices at my workplace and they are all set to 2 stop bits.

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Cheers dude. Well I'm using the light blue cisco cable as supplied with my router.

The only thing is that my machine doesn't have a serial port built-in except for the mobo header, so I had to connect one of those adapters that fit in a PCI bracket and hook up to the COM header via a small ribbon cable. This essentially gives me an available serial port on the box. Do you think this adapter bracket might be wired incorrectly?

Anyway I will go an check it on another box somehow to verify.

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Check this out.

Installing Minicom to connect to Cisco router using console cable.

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Reply to
David Sudjiman

There are at least _two_ different pin-assignement for those headers. Always use that cable which came with the MoBo.

Have one of those LED-boxes ready and look at it with the port at rest and with minicom running. Then, use a paperclip to short the pin's 2 and 3; all keys pressed should come to the screen (IF you DISabled Hardware-Hanshake).

Greetings, Holger

Reply to
Holger Petersen

Using kermit:

In my home directory I have in .kermrc: set file type bin set file name lit set rec pack 1000 set send pack 1000 set window 5 set CARRIER-WATCH OFF set prompt Linux Kermit>

(The CARRIER-WATCH OFF line is the important one iirc)

Then call kermit with:

kermit -l /dev/ttyS0 -p n -8 -c

I use this to connect to a variety of Cisco devices (routers, switches)


Reply to
Claude R Trepanier

Yeah, I think that you've hit the nail on the head Holger. I was using a bracket stolen from an old P100 since my mobo didn't come with one.

I hadn't realized that there could be different standards for the header pinouts, but that seems to have been the problem. It also explains why the cisco was only seeing noise on the line.

Anyway, thanks to all for your extremely helpful contributions. My solution was to actually take David's advice and go out and buy a USB-Serial converter.

I ended up getting the Aten UC-232A

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which works perfectly using the CONFIG_USB_SERIAL_PL2303 module in Linux.

Cheers guys!

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