2.2 COM1~COM2: RS-232 Interfaces
The UNO-1170 offers two standard RS-232 serial communication inter- face port on COM1 and COM2. Please refer to A.2 for pin assignments.
2.3 COM3: RS-232/422/485 Interfaces
The UNO-1170 offers two RS-232/422/485 serial communication inter- face ports, and they are COM2 and COM3. Both port can be configured individually to either RS-232, RS422/485 by using on-board jumpers.
Please refer to A.3 for pin assignments and Table 2.1 lists the default set- ting of each port.
Table 2.1: COM3 Default Settings
COM Port | Default Setting |
| |
COM3 | RS-422/485 |
| |
2.3.1 TI 16C550 UARTs with 16-byte Standard
Advantech UNO-1170 comes standard with TI 16C550 UARTs contain- ing 16 bytes FIFOs. These upgraded FIFOs greatly reduce CPU overhead and are an ideal choice for heavy multitasking environments.
2.3.2 Jumperless RS-422/485
In RS-422/485 mode, UNO-1170 automatically sense signals to match RS-422 or RS-485 network. No need to change jumpers.
2.3.3Automatic Data Flow Control Function for RS-485
In RS-485 mode, UNO-1170 automatically senses the direction of incom- ing data and switches its transmission direction accordingly. Therefore no handshaking signal (e.g. RTS signal) is necessary. This feature lets you simply and quickly build an RS-485 network with just two wires. More importantly, application software previously written for half duplex RS- 232 environments can be maintained without need for modification.