SC105 CS I/O to RS-232 Interface
6
5.1 RAD Modem – Two Way
FIGURE 5-1. Two Way Communication
When using Campbell Scientific’s data logger support software to
communicate through the SC105/RAD modem, “Set-up” the link as a direct
connect between the data logger and the desired COM port. Start two way
communication using the
Connect
button on the tool bar and the
Connect
button in the
Connect
window.
5.2 RAD Modem Wiring and Grounding
shows a typical set-up of the RAD modems. Installation is as
follows:
1. Set the DCE/DTE switch on the back of the RAD modem connected to
the SC105 to DCE. For a RAD modem connected to a PC, set the
DCE/DTE switch to DCE. For a RAD modem connected to a serial
printer, set the DCE/DTE switch to DTE.
2. Select a cable with two or more twisted pairs. Direct burial rodent or
gopher resistant cable is recommended.
3. Wiring connections are made as shown in FIGURE
. Note wires
labeled A and B are one twisted pair of the cable. Wires labeled C and D
are the other twisted pair.
4. Transients induced on the communication line may damage any
electronics connected at either end of the line. To decrease the chances for
damage, spark gaps should be installed as shown in FIGURE
. The
transient protection shown may be purchased from Campbell Scientific
). Spark gap wiring is straight through such that pin to pin
continuity exists between the two modems. If the modems are installed
entirely within a building, the transient spark gap protection is probably
not needed.
4-WIRE UNCONDITIONED
TELEPHONE LINE
OR
TWO TWISTED PAIRS
SRM
9 TO 25 PIN
ADAPTOR
SC105
DATALOGGER
PC
SRM
