for example i am writing any script as follows...
system script add .....
/interface ethernet monitor ether1 once do={
:if ($rate = "10Mbps") do={
/system.........
}}
or
i want to get sms instant by the router when any user is active
script is working when i press "run script" button. but i want the script always check the variables and when rate =10Mbps start do command.i know i can use "system scheduler" bu i want to know if i have another possibility?

In this case, no.
In other places there is sometimes the option to run a script when a certain event occurs, e.g. a PPP connection is made, a DHCP lease is issued, etc.
But not for ethernet connection.

Actually, you could use netmonitor.... I think that's what it's called.

Once you reach a threshold, either in our out, the script is run.

Sent from my cell phone. Sorry for the errors.

mmm I understand.. no alternative ... i still like MİKROTİK Thnks for support...

Traffic Monitor... but that monitors the actual transmit/receive bitrate, not the negotiated rate of ethernet.
May you can somehow use it.

YES İ USE TRAFFIC MONITOR... THNKS