other
sources
such
as
nearby
mains
cables.
As
a
general
rule,
if
you
have
a
noise
issue,
it
is
worth
trying
to
add
a
cheap
100-120 Ω
resistor
across
RS-485
lines.
8.2
Maintenance
No
regular
maintenance
is
needed
for
the
SDM-SIO1A;
however,
occasionally
operating
system
upgrades
are
released
to
add
enhanced
features
or
to
correct
bugs.
The
operating
system
is
normally
published
in
the
Support
section
of
our
website
at
.
8.2.1
Upgrading
the
operating
system
In
the
unlikely
event
that
the
operating
system
of
the
SDM-SIO1A
needs
to
be
upgraded,
this
can
be
achieved
by
connecting
it
to
a
computer
and
using
the
Campbell
Scientific
Device
Configuration
Utility
to
load
the
operating
system.
(This
program
can
be
downloaded
free
of
charge
from
The
SDM-SIO1A
needs
a
reliable
source
of
12V
power
connected
in
the
standard
way.
It
also
requires
a
cable
similar
to
that
shown
in
to
connect
to
an
RS-232
port
on
the
computer.
However,
there
is
no
requirement
to
connect
any
handshaking
lines.
Start
Device
Configuration
Utility
and
select
the
SDM-SIO1A
device.
(The
SDM-SIO1A
device
may
not
be
available
in
older
versions
of
the
software.
New
versions
can
be
downloaded
from
the
Campbell
Scientific
website
at
.)
Follow
the
instructions
for
that
device
to
load
a
new
operating
system.
At
the
end
of
the
process,
a
success
message
will
be
shown
if
successful.
During
the
loading
of
the
operating
system,
do
not
disturb
or
disconnect
power
to
the
SDM-SIO1A,
otherwise
it
may
need
to
be
returned
to
the
factory
for
repair.
When
following
this
process
with
the
SDM-SIO4A,
it
is
necessary
to
run
this
process
four
times,
connecting
to
each
serial
port
in
turn.
This
is
because
each
serial
port
has
its
own
microprocessor
with
each
holding
their
own
copy
of
the
operating
system.
8.2.2
Operating
system
signature
errors
The
operating
system
is
stored
in
flash
memory.
When
a
new
version
is
loaded,
a
checksum
signature
is
automatically
created
the
first
time
its
run.
This
checksum
is
stored
in
memory.
This
signature
value
can
be
read
back
using
the
data
logger
and
compared
to
the
signature
supplied
with
the
operating
system
version
that
was
just
loaded
(contact
Campbell
Scientific
if
you
need
to
do
this).
If
the
SDM-SIO1A
is
not
operational
or
is
exhibiting
random
faults,
the
flash
memory
may
be
corrupted.
This
is
a
very
unlikely
event
due
to
the
robust
nature
of
the
flash
device
used.
The
unit
automatically
checks
the
flash
memory
against
its
signature
upon
power
up.
If
an
error
is
found,
it
SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
29