Campbell Scientific SC932 9-Pin to RS-232-DCE Interface - Manual (Page 13)

SC932 9-Pin to RS-232-DCE Interface
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4.3 RAD Modem - Two Way or One Way
FIGURE 6. Two Way or One Way Communication
In the jumper configuration shown in Figure 6, the communication mode, two
way or one way is determined by the modem enable line. Communication is
two way if the modem enable line is high, one way if modem enable is low. In
this mode, the SC932 and RAD modem combined will require about 2 mA
while inactive and less than 20 mA while active.
Two way setup and connect: same as two way only. One way setup and
connect: same as one way only.
4.4 RAD Modem Wiring and Grounding
Figure 7 shows a typical setup of the RAD modems. Installation is as follows:
1. Set the DCE/DTE switch on the back of the RAD modem connected to the
SC932 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. A recommended direct
burial rodent resistant cable is listed below. They also sell several gopher
resistant cables for even greater protection.
Company Part Number AWG.
Anixter F-02P22BPN 22
Tel: 847-677-2600
http://www.anixter.com
3. Wiring connections are made as shown in Figure 7. 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 7. The