Why the P-Web panel PCD7.D44WT5R crash/reboot if the user access the setup menu?

FAQ #102022

If the user want to access the setup menu of the P-Web panel, then it’s possible that the application program on the P-Web panel crash/reboot and the access to the web-page is no more responsive.

The problem occurs only if the user want to access the setup menu and if the user has set a password to access the setup menu and uses the software watchdog on the application program. 

Error description:

This issue is caused when the setup menu of the P-Web panel is password protected and a software watchdog is implemented in the application program. 

Depending of the used firmware, the combination of those two points cause the panel to:

FW versionbehaviour
FW =< 1.28.11P-Web panel freezes, program stop working until a power 
FW>= FW 1.28.22P-Web panel does reboot, also the application program does reboot

every time the users want to open the setup menu while application program is running.



The solution consists to increase the timeout time for the software watchdog to 800ms.

Opening the setup menu on the P-Web panel slows down the program in that way that the software watchdog is executed and the whole P-Web panel is rebooted. 

To avoid this, the system watchdog time has to be increased. 

This can be done over a CGI instruction or IL programming.

The CGI instruction has to be done over a Web-Browser and the P-Web panel should be available via LAN, with a IP address.

FW 1.28.22 or newer must be used.


Workaround with CGI instruction.

1. Be sure to have a ethernet connection to the P-Web panel

2. Open the web-browser and execute the CGI command: 

3. Control if the set settings are been set correctly: 

4. To save the configuration the following command ha to be executed: 


When it is not saved, the setting will go back to default when the controller does as restart. 

Attention: This command should be used exclusively in this case.


Workaround for IL programming:

Use the IL instruction 'SYS.WriteTag' to set the software watchdog to 800ms.

CSF    S.SF.SYS.Library      ;Library number
          S.SF.SYS.WriteTag         ;Write Tag
          Watchdog_R_name      ;1 X|R IN, Registry name
          Watchdog_T_name      ;2 X|R IN, Tag name
          Watchdog_value      ;3 R|K IN, Tag Value parameter type
          Watchdog_value      ;4 X|R IN, Tag Value
          Program_Status              ;5 R OUT, Status

The IL program is attached to this FAQ and can be added to the PG5 project by using the function 
'Program files, Add Files'

Do not set the software watchdog value differently as described since it could damage the P-Web Panel. 

Related Files:


PCD7 / D443WT5R

Last update: 05.06.2018 12:43

First release: 01.06.2018 10:33

Views: 2

The requested software / document is no longer marketed by Saia-Burgess Controls AG and without technical support. It is an older software version which can be operated only on certain now no longer commercially available products.