I am in the process of trying to design a circuit that will have four RS485 RTU Modbus ports, two acting as clients and two acting as servers, on which I will connect up to fifteen sensors. I am thinking of using a MAX485 transceiver to convert from serial ports to Modbus.
From my understanding, for this to work, the MCU requires four serial ports for this, one for each chip.
Is there a smarter way of doing this kind of communication without needing an MCU with four serial USART ports, which are not that common and are expensive?
Is it possible to just use one port and multiplex it to four different transceivers?
How many serial ports do I need for two client and two server Modbus ports to run simultaneously?
The reason I want so many Modbus ports is that, even though in theory, one Modbus can handle 32 sensors, I think.
In practise, every commercial product we tried struggles past fifteen sensors and we have more than fifteen sensors.