How to set a data cap/data limit alert on a Digi WR21?

I would like to set up either a data limit on the device or an alert on the device that would let me limit the amount of data that the modem uses. I would like to do this on the PPP network or the mobile network as this device uses a SIM card. Any help would be greatly appreciated. Thanks.

one solution is to use python with the saros module. use saros to call whatever command which displays how much data going out or in. When that value exceeds the limit, do whatever.

You can look up the saros commands in the transport users guide on the Digi support website.

Look for the dlwarnkb and dlstopkb commands in the manual.