Rs-485; Figure 20: Terminator's Switch - CipherLab 5000 Hardware Manual

2.2.3 RS-485

Connections between every two terminals are set up through RS-485 interface. When
more than two of the terminals are connected (as a multi-station system), a host only
needs to connect to the first one terminal (master) and it can then communicate with
the rest terminals (slave).
On the last slave device, a termination resistor is usually essential. There is one
terminator on the PCB of each terminal, and a DIP switch (s1) is beside JP3. When
the terminal serves as the last one slave device, please turn on the switch.

Figure 20: Terminator's switch

Slide the DIP switch to the right position on the last salve device.
To establish such RS-485 connection, the following settings need to be done first on
the hardware of the terminals. For preloaded applications, set parameters from the
front panel by entering the Setup Menu.
Line Connection:
Only the device connected to a host is named "Master", the rest are all "Slave".
Station ID:
Assign a unique ID (01 ~ 99) to each terminal.
Maximum station ID:
Set a value (01 ~ 99) as the maximum station ID of the polling list on the Master.
For RS-485 connection without any repeaters, up to 32 stations can be connected.
32
Installing 5000/5100:
>> Also see Section 3. System Architecture
Wiring