Figure 2.2:Rear Panel; Rs-232/422/485 Interface (Com1~Com8); 16Pci954 Uarts With 128-Byte Standard; Rs-422/485 Detection - Advantech UNO-4678 User Manual

Figure 2.2: Rear Panel

2.2 RS-232/422/485 Interface (COM1~COM8)

The UNO-4678 offers eight RS-232/422/485 serial communication inter-
face ports: COM1 and COM8. Please refer to Appendix A.3 & A.4 for
their pin assignments. The default settings of COM1 through COM8 are
all RS-232.

2.2.1 16PCI954 UARTs with 128-byte standard

Advantech UNO-4678 comes with 16PCI954 UARTs containing 128
byte FIFOs.

2.2.2 RS-422/485 detection

In RS-422/485 mode, UNO-4678 automatically detects signals to match
RS-422 or RS-485 networks. (No jumper change required)

2.2.3 Automatic Data Flow Control Function for RS-485

In RS-485 mode, UNO-4678 automatically detects the direction of
incoming data and switches its transmission direction accordingly. So no
handshaking signal (e.g. RTS signal) is necessary. This lets you conve-
niently build an RS-485 network with just two wires. More importantly,
application software previously written for half duplex RS-232 environ-
ments can be maintained without modification.
11 Chapter 2