1
SC929 RS232 INTERFACE
The SC929 temporarily connects a Campbell Scientific battery-powered PC to a datalogger for data
retrieval and program transfer. This interface is typically used in remote locations.
1. SPECIFICATIONS
Operating
temperature: -25
°
C to +50
°
C
Power:
Powered by datalogger; current
consumption typically 8 mA
Connections: 9-pin male; connects to
datalogger
9-pin female; configured as DCE,
connects to AT-type portable PC
Length:
2 m (6 ft.) cable fitted with two
9-pin ‘D’ connectors
Weight:
225 g (
∼
8 oz.)
2. APPLICATION
The SC929 provides a two-way conversion
between datalogger logic levels (0 V low, 5 V
high) and RS232 logic levels (e.g., -8 V low, + 8
V high). It may be used in applications where a
battery-powered laptop is taken to the field to
communicate with the datalogger (e.g., transfer
data or programs, set clock, monitor data, etc.).
It provides a neat, single-cable alternative to an
SC12 cable, 7026 cable, and an SC32A
Interface, but with some differences (see
adjoining note).
NOTE:
There are some significant differences
between the SC929 and the SC32A:
a.
The SC929 does not provide opto-
isolation. To prevent ground loops, do
not use the SC929 with a computer
directly connected to power, powered
AC, or other ground-referenced power
supplies.
b.
Unlike the SC32A, the SC929
consumes significant levels of power
from the datalogger. To avoid
unnecessary power drain, disconnect
the SC929 from the datalogger serial
I/O port when the SC929 is not in use.
c.
The SC929 does not have the jumper
option that is available with the SC32A
and in certain situations odd characters
may appear on the PC screen.
However, this will not affect the correct
operation of Campbell Scientific
software.
CAMPBELL
SCIENTIFIC
INC.
CR10X
MADE IN USA
WIRING PANEL NO.
EARTH
DIFF
SE
AG H L AG H
L AG H
L AG
G
G
E3 AG
4
5
6
7
8
9
10
11
12
G G G G
12V 12V
SWITCHED
12V
G 12V
POWER
IN
SERIAL I/O
SE
DIFF
AG H L AG H
L AG H
L AG
G
G
E1 E2
1
2
3
1
2
3
4
5
6
G 5V 5V P1 P2
C8 C7 C6 C5 C4 C3 C2 C1
CONTROL
12V
SWITCHED
FIGURE 1. The SC929 connects the datalogger’s Serial I/O with a laptop’s serial port for
two-way communication.
