Hello dear Asimo

you can not use siemens repeater for modbus communication according it's own documentation. You should use third parties products e.g. "ADAM-4510 RS-422/485 Repeater".

Please refer to document No. A5E02486680-AK V4.2, 09/2016 , Page 1193.

https://support.industry.siemens.com/cs/us/en/view/109741593

Good luck and hope hear you soon.