MB master variable "INIT_OK"

Hello,

Im using Modbus RTU RS485 on a S7-1214C DC/DC/DC to communicate with a heat pump.
The communications works however it sometimes crashes for some reasons. I have to reset manually online the INIT_OK boolean of the Modbus Data block (I'm using TIA Portal V14 SP1 update 7) by forcing the value of the bit to 0 in order to reset the communication.
I would like to reset this boolean in my program in case of crashe but i can't because :

"access to private and internal variables is not authorized"

Is there any way to modify the variable in my program ?

Thank you in advance,

Quentin Z