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System Configuration
T801-4 Installation and Operation Manual
© Tait Electronics Limited September 2007
4.1
Setting the Links on the System Interface Board
The system interface board has several sets of links which can be used to
configure the operation of the T801-4. These links can be left in the factory
default positions for most T801-4 systems. However, some system
configurations will require some links to be changed. These changes are
described in detail in the following sections.
The following table describes the function of these links. The factory
default positions are shown in
bold
text. The location of the links is shown
in
Figure 4.1
.
Link
Description
Pins
Position
Function
W303
selects the RS-485 termination
resistor for the 1PPS input on
PORT A
(or pins 7 and 8 of
PORT B
- see links
W301 and W302 below)
2
fitted
120
Ω
ohm termination resistor is in
circuit across this RS-485 input
not fitted
termination resistor is not in circuit
W304
selects the RS-485 termination
resistor for the 1PPS input on
PORT B
(pins 1 and 2)
2
fitted
120
Ω
ohm termination resistor is in
circuit across this RS-485 input
not fitted
termination resistor is not in circuit
W305
selects the type of 1PPS input on
PORT A
3
1–2
1PPS RS-485 input is active
2–3
1PPS TTL input is active
(1PPS RS-485 is disabled)
W301
and
W302
configure the RS-485 I/O on
PORT B
(pins 7 and 8)
4
1–2 and 3–4
pins 7 and 8 are a 1PPS RS-485 output
2–3
pins 7 and 8 are a 1PPS RS-485 input
(this also disables the 1PPS RS-485
input on
PORT A
)
W400
controls the RS-485 driver on
PORT B
3
1–2
RS-485 driver for the 1PPS output is
disabled (must be used in conjunction
with W301 and W302)
2–3
RS-485 driver for the 1PPS output is
enabled
W401
prevents DIP switch 1 from disabling
the internal GPS receiver
2
fitted
normal operation of DIP switch 1
not fitted
DIP switch 1 is prevented from
disabling the internal GPS receiver