22
Description
T801-4 Installation and Operation Manual
© Tait Electronics Limited September 2007
DIP SWITCHES
The DIP switches are used to change the configuration of the T801-4.
Some switches are used in combination with other switches, and some are
used only in certain system configurations (these configurations are
described in
“System Configuration” on page 49
).
The following table describes the function of each switch. The switches are
on when in the up position.
h
Switch
State
Function
1
on
a
enables the external 1PPS RS-485 input on
PORT B
(pins 7 and 8)
configures the 1PPS VALID I/O signal line on
PORT B
as an input (pin 4)
off
b
disables the external 1PPS RS-485 input on
PORT B
(pins 7 and 8)
enables the internal GPS receiver
2
c
on
external GPS receiver on
PORT A
is selected
off
internal GPS receiver or external 1PPS RS-485 input on
PORT B
d
is selected
3
e
on
the 1PPS RS-485 output
PORT B
is left running when the 1PPS signal is invalid (i.e the 1PPS
signal is not based on a valid GPS fix)
off
the 1PPS RS-485 output
PORT B
is disabled
f
when the 1PPS signal is invalid (i.e the 1PPS
signal is not based on a valid GPS fix)
4
e
on
the 1PPS TTL outputs are left running when the 1PPS signal is invalid (i.e the 1PPS signal
is not based on a valid GPS fix)
off
the 1PPS TTL outputs are disabled
f
when the 1PPS signal is invalid (i.e the 1PPS signal is
not based on a valid GPS fix)
5
g
on
enables a GPS receiver (1PPS RS-485 input) changeover whenever GPS and /or oscillator
alarms occur
off
disables the GPS receiver changeover
6
h
on
GPS receiver (1PPS RS485 input) changeover triggered only by an oscillator alarm
off
GPS receiver (1PPS RS485 input) changeover triggered by oscillator and/or GPS alarms
7
g
on
enables the 1PPS VALID IN signal line (pin 5 of
PORT B
)
off
disables the 1PPS VALID IN signal line (pin 5 of
PORT B
)
8
on
configures the 1PPS VALID IN and 1PPS VALID I/O input lines to accept steady state input
signals
off
configures the 1PPS VALID IN and 1PPS VALID I/O input lines to accept pulsed input
signals (from the QS
2
RSU with version 3 and later firmware)
a. Set this switch on when the T801-4 is supplied by the 1PPS RS-485 input from the QS
2
RSU.
b. Set this switch off when the internal GPS receiver is fitted (the 1PPS RS-485 input [PORT B] is disabled).
c. The GPS SELECTED LEDs to the right of the DIP switches indicate which 1PPS source is active.
d. When switch 1 is on.
e. The setting of DIP switches 3 and 4 will depend on which GPS receiver is used. Refer to
“1PPS Outputs” on
page 33
for more information.
f. After the fault output delay period (refer to
“Fault Output Delay” on page 33
).
g. Set this switch on for a system configuration consisting of two 1PPS RS-485 inputs (with associated VALID lines)
from a system with dual GPS receiver QS
2
RSUs (refer to
“T801-4 with Dual QS
2
RSU Receivers” on page 65
).
h. The options provided by switch 6 are available only when switch 5 is on.
