COM220 Telephone Modem
TABLE 1. Dataloggers that Require Direct
12 VDC Connection to COM220
CR10(X) with silver wiring panel
CR10(X) with black CR10 wiring panel (P/N 8032)
CR500⎯serial number 1764 or lower
3.2 Connecting to Earth Ground
Connect the green 14 awg grounding wire (provided with the COM220) to the ground terminal (GND) on the COM220 and to the enclosure’s earth ground connection. If the site does not have a grounded enclosure, then connect the ground wire directly to an earth ground connection. The datalogger ground should also be tied to the earth ground.
CAUTION The modem must be grounded for its transient protection to work.
3.3 Telephone to MD485 or Telephone to RF Systems
Telephone to MD485 or telephone to radio configurations can be utilized for communicating with multiple dataloggers through one telephone line. For telephone to MD485 or telephone to radio communications (with no datalogger router), the COM220 should be set for ME mode. The COM220 and MD485 should be set to the same baud rate. When using a PakBus network with a datalogger configured as a router, the COM220 can be set for SDC7 and the radio for SDC8, or vice versa. Contact a Campbell Scientific Applications Engineer for more information. In addition, Appendix A.4.4 includes example programs for both a router datalogger and a remoter datalogger communicating by telephone to MD485 or telephone to radio.
3.4 Telephone Service
The goal of the telephone company is to provide you with the best service it can. In order to do this, it may occasionally be necessary for them to make changes in their equipment, operations, or procedures. If you have any questions about your telephone line, such as how many pieces of equipment you can connect to it, the telephone company will provide this information upon request. If the telephone company requests information concerning the equipment which you have connected to your telephone line, the FCC registration number and the ringer equivalence number (REN) of the COM220 are listed on its label. Additional technical information from the FCC and IC on the COM220 is available in Appendices D and E, respectively.
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