Campbell NW8002, Инструкция по эксплуатации

Страница: 18 / 39

SECTION 1. WEATHER STATION DESCRIPTION AND INSTALLATION
1-13
FIGURE 1.7-1. NW8002 Station Grounding
1.8 SRM-6A RAD MODEM
The SRM-6A Rad Modem consists of two
modems, one at the datalogger site and one at
the computer site. The modem at the
datalogger site is connected to the CR10
through the SC932. The modem at the
computer site is connected to the computer
through a 25 pin RS232 serial port. The two
modems are connected via 4-wire
unconditioned telephone line, or two twisted
pairs. (Figures 1.8-1 and 1.8-2)
1.8.1. INSTALLATION OF RAD MODEM AND
GROUNDING
Figure 1.8-1 shows a typical setup of the RAD
modems. Installation is as follows:
1. Select a direct burial cable with two twisted
pairs. Two recommended types of cable are:
Two Cables: Toro shielded/armored cable
P-7162-D-A-1
or
Anixter F-02P22BPN (Rodent Proof) 22
AWG(tel. 708-677-2600)
2. Disassemble the SRM-6A Modem to
connect the wire. Wiring connections are
made as shown in Figure 1.8-1. Note wires
labeled A and B are one twisted pair of the
cable. Wires labeled C and D are the other
twisted pair. Make sure that the switch
inside both modems is configured for DCE.
3. 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 are installed
at each end as shown in Figure 1.8-1.
NOTE: The SRM-6A at the weather station
is already wired to the spark gaps.