2.6.2
Channel 2 - RS-485
Page 2-6
PCM-DSPIO/J1708 OPERATIONS MANUAL
981117
WinSystems - "The Embedded Systems Authority"
U1 - Not Installed
U3 - Installed
U4 - Not Installed
1 o o 6
2 o o 7
3 o o 8
4 o o 9
5 o
J2
CH2 DB9
Jumper Positions
Driver IC Status
I/O Connector Pin Defs
N/C
TX/RX+
TX/RX-
N/C
GND
TX/RX+
TX/RX-
N/C
N/C
1 o
2 o
3 o
1 o
2 o
3 o
J3
R2
R3
R4
TX/RX+
TX/RX-
vcc
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
may trans mit, or have its trans mit ter en -
abled at a time. The trans mit ter En -
able/Dis able is con trolled by Bit 1 in the
Mo dem Con trol reg is ter (RTS). When set,
the trans mit ter is en abled, 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.
