DUAL- AND QUAD-PORT USB HUBS
Table 4-2. DIP-switch SW4 settings.
Switch | Switch | | | Port | | Description | RS-485 | RS-422 |
Setting | Number | | | | | | | | |
| | | | | | | | | |
L | SW4-1 | 1 | | | TX+ | to RX+ | ON | OFF | |
L | SW4-2 | 1 | | | TX- | to RX- | ON | OFF | |
T | SW4-3 | 1 | | | Termination | ON | ON | |
PD | SW4-4 | 1 | | 1K Pull-Down | ON | OFF | |
PU | SW4-5 | 1 | | 1K Pull-Up | ON | OFF | |
L | SW4-6 | | 2 | | TX+ to RX+ | ON | OFF | |
L | SW4-7 | | 2 | | TX- to RX- | ON | OFF | |
T | SW4-8 | 2 | | | Termination | ON | ON | |
PD | SW4-9 | 2 | | 1K Pull-Down | ON | OFF | |
PU | SW4-10 | 2 | | 1K Pull-Up | ON | OFF | |
| | | | | | | | | |
L = Loops TX+ to RX+ or RX- to TX- for two-wire operation.
T = Adds a 120-ohm termination resistor between RX+ and RX-.
PU = Pull-up. Adds a 1 K-ohm pull-up resistor to RX+.
PD = Pull-down. Adds a 1 K-ohm pull-down resistor to RX-.
Switch SW3 Settings
To select RS-485 mode (4-wire or 2-wire operation) or RS-422 mode (4-wire operation), set the DIP switch labeled SW3 on the circuit board. (See Figure 4-2 and Table 4-3.)
Figure 4-2. RS-422/485 interface configuration.
NOTE
Switch positions SW3-1 and SW3-2 are for Port 1 and switch positions
SW3-3 and SW3-4 are for Port 2.
