Steps to troubleshoot serial ports on NodeGrid Serial Console

Steps to troubleshoot serial ports on NodeGrid Serial Console

1) Open ssh session and login as admin user

2) Verify serial statistics of specific port: show system/serial_statistics/<port number>

a) Example of port 7

[admin@nodegrid /]# show system/serial_statistics/7

7

port: 7

device name: cisco

speed: 115200

rx bytes: 33829054

tx bytes: 165883

rs-232 signals: RTS DTR

cts shift: 1563

dcd shift: 2520

frame error: 0

overrun: 0

parity error: 0

break: 260

buffer overrun: 0

 

b) ‘Rx bytes’ is not equal zero: target device sent chars to NodeGrid (unknown time)

 

3) Reset serial statistics of specific port and confirm:

a) cd systems/serial_statistics

b) reset_statistics <port number>

c) show <port number>

d) Example for port 7:

[admin@nodegrid /]# cd system/serial_statistics/

[admin@nodegrid serial_statistics]# reset_statistics 7

[admin@nodegrid serial_statistics]# show 7

7

port: 7

device name: cisco

speed: 115200

rx bytes: 0

tx bytes: 0

rs-232 signals: RTS DTR

cts shift: 0

dcd shift: 0

frame error: 0

overrun: 0

parity error: 0

break: 0

buffer overrun: 0

 

4) Disable specific managed device, and commit

a) set /settings/devices/<device_name>/access/ mode=disabled

b) commit

c) Example for device ‘cisco’ (that is in serial port number 7 as showed in serial-statistics)

[admin@nodegrid /]# set settings/devices/cisco/access/ mode=disabled

[+admin@nodegrid /]# commit

 

5) Open another session to NodeGrid and log-in as root

a) Launch ‘microcom’ at shell prompt that opens communication with the serial port:

microcom -s <speed> /dev/ttyS<port_number>

b) Try to communicate with device (to close microcom type Ctrl-X)

c) Example for port number 7 - speed 115200 (as showed in serial statistics)

root@nodegrid:~# microcom -s 115200 /dev/ttyS7

cisco login:

 

NOTE: If output shows garbage, stop microcosm (Ctrl-X) and try again with different speed.


6) Verify port serial statistics in admin session (step 2)

a)  show system/serial_statistics/<port number>

b) Example for port 7 - no problem (rx bytes not equal 0 and there is no error)

[admin@nodegrid /]# show /system/serial_statistics/7

7

port: 7

device name: cisco

speed: 115200

rx bytes: 282

tx bytes: 5

rs-232 signals: RTS CTS DTR DSR CD

cts shift: 3

dcd shift: 2

frame error: 0

overrun: 0

parity error: 0

break: 0

buffer overrun: 0

 

7) Enable specific managed device after, and commit

a) set /settings/devices/<device_name>/access/ mode=enabled

b) commit

c) Example for device ‘cisco’ (that is in serial port number 7 as showed in serial-statistics)

[admin@nodegrid /]# set settings/devices/cisco/access/ mode=enabled

[+admin@nodegrid /]# commit

 


 

Results:

1. If serial statistics shows CTS, DSR or CD signals, a device is connected and it is on.
If none of these signals are shown, there may be a device connected that does not implement all RS232 signals. This is common in some network switches.

2. If there is no output when executing microcom and the statistics shows 0 rx-bytes and no errors:
- the cable is wrong, or
- the target device is off, or
- there is no device connected.

3. Errors (including buffer overrun) indicates a mismatch in the serial port config (i.e. parity, data bits, stop bits).



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