Campbell Scientific COM220 56k Phone Modem - Manual (Page 9)

COM220 Telephone Modem
1. Introduction
1.1 General Description
The COM220 modem is a selectable-baud-rate modem employing the Hayes
AT command set. Its primary use is as a remote-site phone modem connected
to a CSI datalogger. The modem is powered and enabled by the battery-
powered datalogger. When not active, the COM220 draws 100 to 120 µA from
the datalogger’s 12-Vdc output. During a call, it draws about 30 mA.
The COM220 is a replacement for the COM210. However, the COM220
supports both synchronous device communication (SDC) and modem enable
(ME) communication, as well as various ME baud rates (9600 to 115200). The
default setting for the COM220 at shipping is SDC7 (see Appendix A,
Changing COM220 Settings, for details).
The default settings ARE NOT compatible with dataloggers
that have non-PakBus operating systems (for example,
CR510, CR10X, CR23X, CR7, CR5000). However,
compatibility with non-PakBus dataloggers is easily
achieved by changing DIP switch settings (FIGURE 1-1). If
you want to use the COM220 as a drop-in replacement for
the COM210, the COM220 settings should be changed to
modem enable (DIP switch 1 open) and 9600 baud (DIP
switches 3 and 4 open). Instructions for configuring the
COM220 are described in Appendix A, Changing COM220
Settings.
FIGURE 1-1. COM220 DIP switches. Five screws and outer cover
must be removed for access to DIP switches.
IMPORTANT
1