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COM1 - RS- 485
J11
3 2 1
o o o
R17
R14
R11
Important Note: All serial termination components are surface mount 0805 packages. These
should only be installed by surface mount qualified individuals.
Page 2-10
WinSystems - "The Embedded Authority"
J12
1 2 3
o o o
VCC
TX/RX+
TX/RX-
EBC-LP OPERATIONS MANUAL
U24 - Not In stalled
U25 - In stalled
U26 - Not In stalled
RS- 485 NOTE : Be cause RS- 485 uses a sin gle
twisted- pair, all trans mit ters are con nected in
par al lel. Only one sta tion at a time may trans mit or
have its trans mit ter en abled. The trans mit ter
En able/Dis able is con trolled in soft ware us ing bit 1
in the Mo dem Con trol Reg is ter (RTS). When RTS is
set, the trans mit ter is en abled, and when cleared (the
nor mal state) the trans mit ter is dis abled and the
re ceiver is en abled. Note that it is nec es sary to al low
some mini mal set tling time af ter ena bling the
trans mit ter bef ore trans mit ting the first char ac ter.
Like wise, fol low ing a trans mis sion, it is nec es sary
to be sure that all char ac ters have been com pletely
shifted out of the UART (Check Bit 6 in the Line
Status Reg is ter) bef ore dis abling the trans mit ter to
avoid chop ping off the last char ac ter.
COM1 DB9
N/C
1 o o 6
N/C
N/C
2 o o 7
TX/RX+
N/C
3 o o 8
TX/RX-
N/C
4 o o 9
N/C
5 o
GND
030530
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