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used
to
the
21X that
a
a
a
a
a
radio
short
modem
SC32A
ribbon
cable
inbrtace
and coax cable
does
not
cover the technical
inbrtace
details for
any
of
these
links.
Those details
Section
6
and
in the individual manuals for the devices.
Data retrievSl
can take place in either
ASCII
or
BINARY.
The BINARY format is five times
more
compact
th41
ASCll.
The
shorter transmission times
for
binary result in lower long distance
telephone charges and
more reliable data
transfer. On "noisy"
links
shofter blocks of data are
SECTION
5.
TELECOMMUNICATIONS
allows
a
computer to retrieve data directly from Final Storage and may be
the
21X and monitor sensor readings in
realtime.
Any user communication with
use of
a computer or
terminal instead of
the
21X keyboard is through
can take place over a variety
of
links
including:
more efficient data transfer, binary data retrieval makes use of a
signature for error
signature algorithm assures
a 99.998% probability that if either the data
or
its
the signature changes.
This section
are
covered
ln addition
detection.
sequence
The
PC208
Support Software
for
PCs and compatibles
contains
the
program
TELCOM
automates data retrieval
and
TEBM
which will upload
and download programs
and monitorltlnput
Storage.
The
PC208
package
has
been designed
to
meet the
most common
needs
in dalalogger support and telecommunications.
This
section in not intended to furnish
sufficient
ddait
to
write Telecommunications software. Appendix
C
contains some details
of
binary data Vansfer
and Campbell Scientitic's binary data tormat.
This sectiorl emphasizes the commands that
a
person would use when manually (i.e., entered by
hand)
interrpgating
or
programming
the
21X
via
a computer/terminal. These commands and the
responses
tl
tnem
are
sent
in
the
American Standard Code for Information lnterchange (ASCll).
The
RemotQ
Keyboard State (Section 5.2) allows the user with a computer/terminal to use the
same
comnlands as the 21X keyboard.
5.1
TELECOMMUNICATIONS
COMMANDS
When the
211X
is rung by
a modem, it answers
(enables
the modem) almost immediately.
Several
carfiage returns (CR) must be sent from
the computQr to allow
the 21X to set its baud
rate
to that
Ff
the modem/terminal (300,
1200,
9600, or 761800). Once
the baud rate is set, the
21X sends
fhe prompt,
*, signaling
that it
is
ready
to
receive
a
command.
GENERAL RULES governing the
telecommu nications
commands are:
1.
*
from datalogger means "ready for
command",
2.
Allcommands are of the
form:
[no.]letter,
where
the number may or may not
be
optional.
3.
Valid characters are
the numbers 0-9, the
capital letters
A-L, the colon (:), and the
carriage return (CR).
4,
An illegal character increments
a
counter
and zeros
the command buffer, returning
*
5-1
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