Campbell Scientific SC105 SC105 9-pin to RS232 DCE Interface - Page 12

SC105 CS I/O to RS-232 Interface TABLE 5-1. Approximate Range, miles and km Data Rate 19 Gauge (0.9 mm) bps miles km 9,600 6.2 10.0 1,200 7.6 12.2 24 Gauge (0.5 mm) miles km 2.8 4.5 3.4 5.5 26 Gauge (0.4 mm) miles km 2.0 3.3 2.5 4.0 5.1 RAD Modem - Two Way 4-WIRE UNCONDITIONED 9 TO 25 PIN PC SRM TELEPHONE LINE OR SRM ADAPTOR TWO TWISTED PAIRS SC105 DATALOGGER FIGURE 5-1. Two Way Communication When using Campbell Scientific's datalogger support software to communicate through the SC105/RAD modem, "Set-up" the link as a direct connect between the datalogger 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 FIGURE 5-2 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. A recommended direct burial rodent resistant cable is listed below. They also sell several gopher resistant cables for even greater protection. Company Anixter Tel: 847-677-2600 www.anixter.com Part Number F-02P22BPN AWG. 22 3. Wiring connections are made as shown in FIGURE 5-2. 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 5-2. The transient protection shown may be purchased from Campbell Scientific (pn 5563 shown in FIGURE 5-2, pn 6536 includes a plastic case, pn 6361 includes hardware for mounting to ground lug of Campbell Scientific 6