How to get server uptime of AIX server results in seconds

In Linux, I can get the server uptime results in seconds (value) by using below command

cat /proc/uptime

But in AIX, we do not have uptime in /proc. If I just type uptime, I get results in days, hours, minutes, but I want to get the output only in seconds like 86400 seconds or 30 seconds or any value. With this output, I want to set an alert from SCOM monitoring tool to create alerts if it is less than 1800 seconds. From SCOM, I can run a shell command.