The APM-10/11 expands a single (host) port to 8 RS-485 ports in a star configuration.
All outgoing data (T+ / T-) is broadcast simultaneously on all 8 ports. The host port interface can be RS-232 or RS-485. An appropriate line terminator must be used at the end of the RS-485 lines. Use line terminators ATM-48 (P/N 470-030) with APM-10, and ATM-87 (P/N 470-034) with APM-11