PP800 Communication with AC800M Time synchronisation

I Have AC800M Controller connected with Process Panel PP835 using Compli protocol. PP835 is a Comli master and AC800M is a Comli salve. Now i need to do time synchronisation between Ac800M Controller and PP835 device. I want my AC800M controller as Time master. How to do this configuration. I red the user manual of PP800. I tried to choose Clock as Controller 1 after downloading i am getting communication error, if i choose Terminal clock., no communication error. Experts advice pls. I cannot use the SNTP setup because in the site system is already established totally 80 nos of PP800 and 80 nos of AC800M controllers are connected. I cannot go with TCP/IP Connection with controllers.