Contec SPI-8451-LLVA User Manual
4. Jumper Setting
SPI-8451-LLVA, SPI-8452-LLVA, SPI-8451-LVA
37
RS-485 Setting
RTS#
JP8: 7-8
TXD#
JP7: 7-8
JP7: 5-6
D
R
RXD#
SERIAL2
1
2
3
4
5
6
7
8
9
JP8: 5-6
JP8: 4-6
120 Ω
120 Ω
DATA-
DATA+
Figure 4.2. RS-485 Setting
I/O addresses and instructions
The table below lists I/O addresses for use as SERIAL2.
Table 4.2. I/O Addresses and instructions
I/O address
DLAB
Read/Write
Register
W Transmitter
holding
Register
THR
0
R
Receiver buffer Register
RBR
02F8H
1
W
Divisor latch Register (LSB)
DLL
1
W
Divisor latch Register (MSB)
DLM
02F9H
0 W
Interrupt
enable
Register
IER
02FAH
X
R
Interrupt ID Register
IIR
02FBH
X
W
Line control Register
LCR
02FCH
X
W
Modem Control Register
MCR
02FDH
X
R
Line status Register
LSR
02FEH
X
R
Modem Status Register
MSR
02FFH X
R/W
Scratch
Register
SCR