Contec PT-S3000HX-DC Series, User Manual

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SERIAL I/O Address and Register Function
The following table lists the I/O addresses in case of SERIAL Port A, B.
Table 6.4. I/O Port Addresses
I/O address DLAB Read/Write Register
03F8H 0 W Transmitter holding register THR
R Receive buffer register RBR
1 W Divisor latch register (LSB) DLL
03F9H 1 W Divisor latch register (MSB) DLM
0 W Interrupt enable register IER
03FAH X R Interrupt ID register IIR
03FBH X W Line control register LCR
03FCH X W Modem control register MCR
03FDH X R Line status register LSR
03FEH X R Modem status register MSR
03FFH X R/W Scratch register SCR
DLAB (Divisor Latch Access Bit): The value in bit 7 of the line control register.
Table 6.5. Function of Each Register < 1 / 4 >
I/O address Description
03F8H
THR: Transmitter Holding Register [DLAB=0]
Register dedicated to write transmitted data to
03F8H
RBR: Receiver Buffer Register [DLAB=O]
Register dedicated to read received data from
03F8H
DLL: Divisor Latch (LSB) [DLAB=1]
Baud rate setting register (LSB)
03F9H
DLH: Divisor Latch (MSB) [DLAB=1]
Baud rate setting register (MSB)