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13 Chapter 2
2.2 RS-232 Interface (COM1~COM2)
The
UNO-3074 offers two
industrial standard
RS-232 serial communica-
tion
interface ports:
COM1
and COM2. Please
refer to
Appendix A.4
for
their pin
assignments.
The IRQ and I/O address range
of
COM1 and COM2
are
listed below:
COM1: 3F8
H
,
IRQ4 COM2: 2F8
H
,
IRQ3
2.3 RS-232/422/485 Interface (COM3~COM4)
The UNO-3074
offers
two industrial RS-232/422/485 serial
communica-
tion interface
ports: COM3 and
COM4. Please refer to
Appendix A.5 for
their
pin assignments.
The default setting of
COM3 and COM4
are
RS-
422/485. (Please refer to section 2.3.4 for how to determine RS-232 or
RS-422/485)
2.3.1
16C550 UARTs
with 16-byte FIFO Standard
Advantech
UNO-3074 comes
with 16C550 UARTs
containing 16 bytes
FIFOs.
2.3.2
RS-422/485 Detection
In RS-422/485 mode,
UNO-3074
automatically detects signals
to match
RS-422 or
RS-485 networks.
(Refer to section 2.3.5)
2.3.3
Automatic Data Flow Control Function for RS-485
In RS-485 mode, UNO-3074 automatically detects the direction of incom-
ing data
and
switches its transmission direction accordingly. So
no hand-
shaking signal
(e.g. RTS
signal)
is necessary. This lets you easily build an
RS-485 network
with Data+, Data- and Ground. More
importantly, appli-
cation
software previously written for full-duplex RS-232
environments
can be maintained without
modification.