These chips feature programmable baud rate, data format, 128-byte dual-port TX buffer, and 384-byte dual-port RX buffer. The RS-232/422/485 and the RS-422/485 transceivers support data rates up to 921.6 kbps for RS-422/485 and 460.8 kbps for RS-232.… The IC1020A has one USB Type B connector and two DB9 male connectors. The IC1021A and IC1022A have one USB Type B connector and four DB9 male connectors. The pinouts for the DB9 connectors are described in Tables 2-1 and 2-2. Table 2-1. RS-422/485 DB9 male connector pin assignments. Page 4
In this case, it is COM3, 4, 5, and 6. However, this assignment will vary from system to system. At this point, the hardware is recognized and ready to use.… This device ships with the following configuration:… • 1 K-ohm pull-up resistance on RX+, and • 1 K-ohm pull-down resistance on RX-. To change this configuration, you must open the box. Do this by removing the four screws located on the bottom. When reassembling, please note that the top and bottom are keyed to fit in only one direction. 4.2 Electrical Interface Selection Each of the two DB9 ports on the IC1020A can be individually configured as an RS-232, RS-422 , or RS-485 interface. Ea Page 6
To configure Port 2 for RS-232, select Jumper E5. You do not need to set any DIP switches to configure Port 1 or 2 for RS-232.… To configure the ports on the Dual-Port USB Hub for RS-422/RS-485 instead of RS-232, select Jumper E7 for Port 1 and Jumper E6 for Port you are running RS-422 or RS-485, you also need to set switch SW4, positions 1 through 10 . For example, to set RS-485 2-wire operation on Port 1, set SW4-1 and 4-2 to ON. For RS-485 4-wire operation, regardless of the interface, SW4-3 and SW4-8 are always set to ON. Pull-down resistor for Port 1 and pull-up resistor for Port 1 can also be set to ON or OFF for RS-422 or RS-485. Page 8
In a two-wire setup, the receiver will not echo back the transmitted… Each of the four DB9 ports on the Quad-Port USB Hub can be set as either RS-422 or RS-485. You do not need to set a jumper to select these options. Instead, you just need to set DIP-switches SW1, SW2, SW3, and SW4. Switch SW2 and SW4 Settings To select either RS-422 or RS-485, set the DIP switches labeled SW2 and SW4 on the circuit board . Table 4-4 lists the possible settings for DIP- switches SW2 and SW4. You can also set termination, pull-up resistance, and pull- down resistance via these switches. Figure 4-3. Switches SW2 and SW4. Switch positions SW4-1, 2, 3, 4, and 5 are for Port 1. Switch positions SW4-6, 7, 8, 9, and 10 are for Port 2.
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