RS232/CAN switch circuit
The MUX chip must have larger supply voltages than the signal voltages. If you route RS232 with the RS232 MUX which is about +/- 12V signal to any of the nine output connectors, there it will get connected to CAN MUX. Therefore the CAN MUX must also have +/- 12V supplies so it does not clamp the signal. You also can't connect CAN and RS232 simultaneously to same connector with the MUXes as that will connect the CAN bus to RS232 lines.