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2.2 RS-232/422/485 Interface (COM1~COM2)
The UNO-3072A/3074A offers two industrial RS-232/422/485 serial
communication 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 deter-
mine RS-232 or RS-422/485).
2.2.1 16C950 UARTs with 128-byte FIFO
Advantech UNO-3072A/3074A comes standard with Oxford
OXuPCI952 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 multitask-
ing environments.
2.2.2 RS-422/485 Jumperless Detection
In RS-422/485 mode, UNO-3072A/3074A 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-3072A/3074A 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.
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Chapter 2
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