I think that will not work, on a Modbus RTU network can only exist a single master, there cannot be other masters, even connected through a Modbus TCP to Modbus RTU gateway
Are you assuming that the masters on both sides can send requests to the slaves on RTU side?
It will work. A Modbus TCP to Modbus RTU gateway knows how to multiplex the serial RTU communications.
That's a Modbus Plus device. Modbus Plus (a licensed protocol) uses a token method for regulating the traffic on the bus. Regular Modbus (the open protoocol) has no such provision, which is why 'only one master allowed at a time'.Even the original BM85 bridge multiplexer from Modicon could let up to 3 Modbus masters talk to 1 slave.
I think that will not work, on a Modbus RTU network can only exist a single master, there cannot be other masters, even connected through a Modbus TCP to Modbus RTU gateway
Are you assuming that the masters on both sides can send requests to the slaves on RTU side?
Even single PLC can have several different (serial) modbus ports and share same data of PLC. Newest writed data wins and is echoed to other ports.
What makes you think that this is not possible, when there is special gateway which have several RS-ports and one TCP?
But OP is question is: one master device, 4 serial slaves and 2 TCP slave. No even need to think that there is collisions as there is only one master.
One or two Serial to TCP gateways is needed.