how Ican show battery voltage for RB450 on hotspot login??
Only via a 3rd party service.
Basically you could have a webserver running somewhere, that is getting the voltage from this machine via the API or SNMP. Then the Hotspot page could have an iframe that shows this info from the webserver. Not elegant, of course. But maybe you don’t even need the login page? Can’t you check it on the webserver directly?
so can I use php and how??
PHP examples: http://wiki.mikrotik.com/wiki/API_PHP_package