PCI Express Boards
Programming Guide
6-5
Control Serial Interface and Termination Resistor for MUE chips
For Moxa boards that use MUE250, MUE450, and MUE850 chips, BAR2, which allocates 16 bytes, is the vector
base address that can be used to control serial interface and termination resistors according to the following
table.
Offset
Bit
Port #
Parameters
0x4
[3..0]
1
0x0 : RS-232
0x1 : RS-422
0xF : RS-485 2W
0xB : RS-485 4W
[7..4]
2
0x5
[3..0]
3
[7..4]
4
0x6
[3..0]
5
[7..4]
6
0x7
[3..0]
7
[7..4]
8
0x8
[7..0]
[8..1]
GPIO – Input
0x9
[7..0]
[8..1]
GPIO direction configuration
0 : Set GPIO direction to input
1 : Set GPIO direction to output
0xA
[7..0]
[8..1]
GPIO – Output (Termination Resistor)
0 : Low (0 Ohm)
1 : High (120 Ohm)
Especially, the interfaces of 4 ports model, such as
CP-114EL and CP-114EL-I,
are using the following offset to
set the interface of port 4.
Offset
Bit
Port #
Parameters
0x4
[3..0]
1
0x0 : RS-232
0x1 : RS-422
0xF : RS-485 2W
0xB : RS-485 4W
[7..4]
2
0x5
[3..0]
3
[7..4]
-
0x6
[3..0]
-
[7..4]
-
0x7
[3..0]
4
For Baud Rate Setting
For General PC Com Port: CLK=1.8432MHz
Div = CLK/(Baud x 16)
But for Moxa Board: CLK=
14.7456
MHz
Div =
CLK
/(Baud x 16)
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