Advantech SOM-5786 Instrukcja Użytkownika Pobierz pdf (Strona 17)

9 Chapter 2

2.2 RS-232/422/485 Interface (COM1~COM2)

The UNO-3072LA offers two industrial RS-232/422/485 serial commu-

nication interface ports: COM1 and COM2. Please refer to Appendix A.5

for their pin assignments. The default setting of COM1 and COM2 are

RS-422/485. (Please refer to section 2.2.4 for how to determine RS-232

or RS-422/485)

2.2.1

16C950 UARTs

with 16-byte FIFO Standard

Advantech UNO-3072LA comes standard with Oxford 16PCI952 UART

(two OX16C950 UARTs, fully software compatible with 16C550) which

containing 128 bytes FIFOs. These upgraded FIFOs greatly reduce CPU

overhead and are an ideal choice for heavy multitasking environments.

2.2.2 RS-422/485 Jumperless Detection

In RS-422/485 mode, UNO-3072LA automatically detects signals to

match RS-422 or RS-485 networks. (Refer to section 2.2.5)

2.2.3 Automatic Data Flow Control Function for RS-485

In RS-485 mode, UNO-3072LA 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 easily

build an RS-485 network with Data+, Data- and Ground. More impor-

tantly, application software previously written for full-duplex RS-232

environments can be maintained without modification.

2.2.4 RS-232/422/485 Selection

COM1 and COM2 support 9-wire RS-232, RS-422 and RS-485 interfaces.

The system detects RS-422 or RS-485 signals automatically in RS-422/

485 modes. To select between RS-422/485 and RS-232 for COM1, adjust

CN28. To select between RS-422/485 and RS-232 for COM2, adjust

CN29.

You can refer to figures below to set the CN28 and CN29.

Note: Please refer to Appendix A.2 Figure A.3 for location

of CN28 and CN29 location.

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