SECTION
2. PC2O1
TECHNICAL
REFERENCE
The
PC201
Clock,
Tape & Serial
I/O
Card
provides
the hardware
necessary to
read or write Campbell
Scientific
casseffe data
tapes and aid in
unattended operation of the
IBM PC.
The
card contains
a
battery
backed up realtime
clock and an
asynchronous
serialcommunications
port
which
may be
configured
as COM|,
COMZ, COM3, or
COM4. The PC201
is addressable to any
l/O
address
in the
PC
l/O
map,
but supporting
software
must be changed if addresses
otherthan COMI, COMZ, COM?,
or
COM4
are used. The
softttrare clock is
implemented with
the
63A3
processor.
lf the PC2O3 Power-up
Control
Box
is
connected
to the PC201,
the
clock
is
synchronized
to the 50 Hz
or 60 Hz signal
originating
from
the
115 VAC
power
line.
When the AC
signal
is not
available,
the clock is maintained
by
a
baftery
powered
16.384
kHz crystal oscillator
on the PC201
card. The
two alkaline
'AAA'
cell batteries
should
be
replaced every two
years.
The clock can be set
with IBMTOCLK and
read with
CLKTOIBM.
The status of the battery
can be checked
by reading the status byte
from
the
PC201 card. Clock
accuracy
without
the
PC203 is
*3
minutes
per
month. With the
PC203,
accuracy
is equal to the
accuracy
of
60
Hz.
The
asynchronous serial
communications
port
is designed to be
functionally
equivalent
to the IBM
Asynchronous Communications
Adapter
with
a couple of exceptions.
The
OUT|
modem
control
line
from
the 8250 UART
on the standard IBM card
is not
used.
The PC201
uses
this output to interrupt the
6303
processor,
causing
it to abort a current command and
insuring
its attention
prior
to issuing
the
6303
a
command.
Another difference
is
that
the PC20l card does
not
provide
a current
loop option for serial
communications.
The
PC201 card is
equipped
with
a 34
pin
rectangular
connector
designed to
provide
a
standard R5232
port
when
proper
cabling
is used.
Other
conductors on the
34
pin
connector
are
used
in
conjunction with eitherthe
PC203 Power-up Control
Box or the Campbell Scientific 9
pin
intefiace.
The
9
pin
inbrtace may
be used directly
with
CampbellScientific's
Model SM16/5M64
or 5M192/5M716
Storage
Modules.
Tape
read/write circuitry
provided
on the
PC201 card reads or writes to Campbell
Scientific
data
cassefte
tapes. Specific
commands are
not
provided
in
the
6303 ROM to accomplish tape
read/write
functions, but commands
are
provided
to
down load
and execute
6303 code from
the PC. This method
allows
flexibility forfuture
variations in tape
formats without requiring ROM alterations.
lnformation
regarding unaftended operation
is contained in the
PC208 Datalogger Support Software
Manual;
a brief summary
of capabilities
is
included here. Softvvare associated
with these functions
is
contained
on the
PC208 diskette. ln combination
with the PC203
Power-up
ControlBox,
the PC can
be
powered
up at a
predetermined
time, execute a
program,
and
power
down without
user assistance.
A
watch
dog
function
is
included
which
powers
the system down, then up,
if
it
is
not
progressing properly
due
to a momentary
power
failure or
program
error. Power-up software allows
the PC to execute
a
given
program
at a
given
time with a watch
dog
to ensure the
proper
completion of
that
program.
Another
function built
into the PC20l card
is the ability to use
the PC
to answer
an
incoming
call.
To
accomplish
this the PC20l
card must be
connected to the PC203
Power
Controller
box,
which
in turn
is
connected
to a suitable
modem such as
the Hayes Smaftmodem.
The modem
must
be set to the
answer
mode
with its
power
left on. An
incoming callactivates the modem
Ring lndicator
line which is
sensed
by
the PC201 card.
The
PC201 card,
in tum,
powers
up the
PC through the PC203 and activates
the
Data
Terminal
Ready
line
to the
modem.
The modem
answers
the call when it
senses the DTR line
active
and sets the Carrier
Detect
line
after
establishing the
carrier signal. At
the
time the
Ring lndicator
is sensed, the
PC201 card sets a timer to
thirty seconds and
powers
the PC
on.
lf
the Carrier
Detect
is
not
sensed within this
time, the
PC is
turned
off.
When
the
Carrier Detect is sensed by the
PC201 card,
the
timer is inhibited
from counting down.
After
the call
is
completed,
the Carrier
Detect
goes
in-active
and
the timer counts
down.
Power is
turned
off 15 or 20 seconds
later when
the
timer
reaches
zero.
2-1