GDS-68XP Operation & Maintenance Manual, Revision 3.5
Page 24
6
INITIAL
SETUP
OVERVIEW
The
GDS
‐
68XP
consists
of
an
electronic
sequencer
that
controls
and
monitors
the
sample
/
measurement
/
purge
operation
and
a
dual
‐
channel
GASMAX
CX
monitor
that
measures
the
raw
sensor
data
(Channel
1)
and
stores
and
displays
the
captured
measurement
(Channel
2).
SEQUENCER
CONTROLS
AND
INDICATORS
To
access
the
GDS
‐
68XP
sequencer,
unscrew
and
remove
the
cover
of
the
gray
explosion
‐
proof
enclosure.
The
length
of
time
between
samples
is
determined
by
the
SEQUENCE
switch
setting.
Sequencer
control
for
testing
and
setup
is
managed
by
two
pushbuttons
(“BYPASS”
and
“RUN”)
located
on
the
sequencer
board,
and
the
state
of
system
(sampling,
purging,
waiting)
can
be
determined
by
viewing
status
LEDs
(“L1”
and
“L2”,
“PUMP”
and
“VALVE”)
also
located
on
the
sequencer
board.
Figure 6-1: GDS-68XP User Interface
The
GDS
‐
68XP
sequencer
monitors
the
output
of
the
GASMAX
raw
sensor
channel
and
flow
switch
and
controls
the
operation
of
the
purge
air
pump
and
3
‐
way
valve.
SEQUENCE
switch
setting
determine
the
length
of
time
between
each
sample
cycle.
There
are
seven
preset
sample
times
and
one
‘on
‐
demand’
setting
that
allows
an
external
PLC
or
DCS
to
command
the
start
of
a
sample
cycle.
Switch
positions
are
numbered
0
to
7,
clockwise
starting
from
the
bottom.
“BYPASS”
“RUN”
“L1”
“L2”
“VALVE”
“PUMP”
“SEQUENCE
SWITCH”