High data usuage out of nowhere

I am using 5 RV50s to grab data via modbus from 4 locations. A master Rv50 is set to grab the modbus data from the other 3 locations. Each site is only being asked for 16 bits of data every minute. Now I do understand that the actual data sent through verizon will be more but overall this is a very small amount of data. The seconds half of this month we have seen more than 5x the data usage than in the first month. I am looking for any help as to why this might be. We have not changed any setting or modified the amount of data being sent.

Hi @Matt1,

Which FW version that RV50 is running? If not latest, please refer to the following link to get the latest FW then recheck whether the problem is resolved.
Because I see some similar issues that have been fixed in the latest release.
Link the latest FW: https://source.sierrawireless.com/resources/airlink/software_downloads/rv50/rv50-firmware-list/#sthash.ouIGWwma.dpbs