Can you get a PPP session's uptime?

RouterOS Scripting
1

Hi,

I would like to know how i will be able to put the uptime of a PPP session in a variable. My logic is as follows…

:global up;
:set up [/interface pptp-client get pptp-out1 uptime];

Any help??

2 
:global up;
/interface pptp-client monitor pptp-out1 once do={
   :set up $uptime;
}
3

THANKS!!