Operator`s manual

SECTION 4. EXTERNAL STORAGE PERIPHERALS
4-5
POWER SUPPLY
The 21X's internal power supply will power the
recorder during periods of data transfer, but will
NOT be available to play, advance, or back-up
tapes. In order to perform these functions
during setup and check-out operations, the
recorder requires 4 alkaline AA batteries or the
120 VAC adapter.
OPERATING TEMPERATURE LIMITATIONS
The cassette recorder is recommended for use
in an environmental operating temperature
range of 0° to +40°C. Temperatures below 0°C
may cause tape speed variation in excess of
that which can be tolerated during playback.
Data Recorded with the RC35 outside the 0°C
to 40°C range may be unreadable.
VOLUME CONTROL
When recording data, the RC35's volume setting
does not matter. The recorder is equipped with
an automatic gain control which controls the
recorded signal level. For playback, a mid range
volume setting is normally required.
CASSETTE TAPES
Normal bias, high quality cassette tapes are
recommended for use with the recorder. The
more expensive high bias chromium oxide tapes
will NOT perform satisfactorily. Although the
use of C-90 tapes is generally successful,
Campbell Scientific recommends the use of C-
60 (30 minutes per side) cassettes. TDK,
Maxell, and equivalent quality cassette tapes
perform well and are readily available. Bargain-
priced tapes have often performed poorly and
are not recommended.
New tapes are often tightly wound, creating
enough drag or pressure to cause the tape
recorder to "pop" out of the record mode. This
potential loss of data may be overcome by fast-
forward/rewinding the entire tape before placing
it in service.
4.3.2 CASSETTE CONNECTOR INTERFACE
CABLES
A Cassette Interface Cable is required to
connect the cassette recorder to the 21X. Two
models are available. The SC92A is a WRITE
ONLY interface. The SC93A READ/WRITE
interface is only necessary if the 21X has
special software for transferring programs via
tape (Appendix B).
The SC92A and SC93A have a combination
backshell circuit card and 9-pin connector which
attaches to the serial I/O connector on the 21X.
The SC92A has two plugs which connect to the
POWER and MIC jacks on the recorder. The
SC93A has three plugs which connect to the
POWER, MIC and EAR (or MONITOR) jacks on
the recorder. Both cables transform 12V from
the 21X to 6V to power the recorder during
periods of data transfer. Additional circuitry
shapes the data signal waveform.
4.3.3 TAPE FORMAT
Data tapes generated by the 21X are read by
the PC201 tape read card for the IBM PC/XT/AT
or by the C20 Cassette Interface. The C20
decodes the tape and transmits the data in
ASCII via a standard RS232 interface.
TABLE 4.3-2. Format 2 Specifications
Data Binary
Low Resolution 2 bytes/data point
High Resolution 4 bytes/data point
C-60 Capacity 180,000 data points
(Lo Res.) (1 side only)
Data Transfer 100 data points/sec.
Rate (Lo Res.)
Block Size 512 Final Storage
locations
4.3.4 CONNECTING TAPE RECORDER TO 21X
The procedure for setting up the 21X and
cassette recorder for transfer to tape is as
follows:
1. Load a cassette in the recorder and
advance the tape forward until the tape
leader is past the recording head. (Internal
batteries or AC power required.)
2. Connect the SC92A or SC93A to the 9-pin
serial I/O port.