2 Application Use-Case of Multiprotocol Transceivers

One of the main applications that utilizes multiprotocol transceivers are Industrial PCs (IPC, also known as single board computers). Modern industrial manufacturing and automation have proliferated IPC into multiple fields including factories, medical, automotive, and retail. Main requirements for IPC design are:

• Robustness against transients to support harsh industrial environment
• Communication versatility- IPC needs to support large number of communication interfaces such as USB, Ethernet, display port, RS-232 and RS-485
• Small form factor. High power dissipation on board necessitates support for higher ambient temperature for semiconductors used

There are pre-dominantly two ways a multiprotocol transceiver is used by system designers:

• Single communication port needing one interface at a time via shared bus/logic lines. So, the port is either a RS-232 or a RS-422/RS-485 interface at one time. Main benefit for the application is there is no need for two physical connectors- same connector can be used as RS-232 or RS-485, so overall space needed on PCB is drastically reduced.
• Two port requiring both interfaces at the same time, but with each port configurable for either RS-232 or RS-422/RS-485.

These usage methods are aimed towards mainly three application scenarios detailed below

• Shared port with on-the-fly configurability: Certain applications need configurable communication port. For example, an industrial equipment’s port is configured as RS-485 for long distance multipoint communications. But during downtime, that port needs to be converted to RS-232 for diagnostics or firmware upgrade. Multiprotocol transceivers benefit such applications by requiring just one device instead of having separate RS-232 and RS-485 transceivers. Additional discrete circuitry to implement seamless switching between both interfaces and enabling/disabling termination for either interface is eliminated as that functionality is now integrated into the Multiprotocol transceiver, shrinking solution size considerably.
• Single port fixed interface: Multiprotocol transceivers comprising of RS-232 and RS-422/RS-485 benefit the applications which just need one interface. Customers can select, test and qualify multiprotocol transceiver, and configure it for either interface. Main benefit is reduced development time and effort, and lower inventory cost of management since now the customers do not have to select different devices for different applications.
• Protocol translation: Multiprotocol transceivers that enable both RS-232 and RS-485 interfaces simultaneously can be used as protocol translator. Certain application scenarios need an equipment’s legacy RS-232 port to be converted as RS-485 for long distance communications. RS-485 inputs and outputs can be connected to RS-232 outputs and inputs to enable RS-232 communication distance extension.