In larger SIS applications the logic solvers can be split into multiple SIS Network domains either due to application size or simply to partition the system. In these implementations each SIS Network domain can contain as many as 32 Domain Global Publishers to exchange data between the controllers within the domain. If a Logic Solver in one domain publishes a secure parameter that is referenced by a Logic Solver in another domain, the publishing Logic Solver must be configured as a System Global Publisher. There are two main layouts that can be used with Multiple SIS Network domains.
It is possible for multiple SIS Network domains to co-exist on one SIS Network ring.
Each domain can contain as many as 32 Domain Global Publishers. If the configuration in this implementation requires any information to be shared between domains, the Logic Solvers publishing the data will need to be configured as System Global Publishers.
For example if a Logic Solver in CTRLR16 references a parameter published by a Logic Solver in CTRLR3, the Logic Solver in CTRLR3 must be configured as a System Global Publisher. Even though the logic solvers are on the same SIS Network ring they are in two different SIS Network domains.
This arrangement does not require the use of SIS Network bridges as all SISNet Repeaters are on the same SIS Network ring and therefore all Logic Solvers have access to the system global data. One downside of this arrangement is that if all the equipment in Domain 2, including the SISNet Repeaters, needs to be powered down then the SIS Network ring is broken affecting the Global data in Domain 1.