COM220 Telephone Modem
You can modify the following COM220 settings with DIP switches:
1)Communication mode (e.g., SDC or Modem Enable)
2)ME baud rate
3)PakBus ready
Additional changes (see examples below) may be modified with Hayes AT commands. Appendix A.2 describes the procedures and commands required to effect the changes described in this section.
Some of the AT command settings one may change are:
Disable
Speaker On/Off and Volume: Default settings have the speaker on only during call establishment and set to a low volume. The speaker may be turned completely off in order to limit the current drain during the connection or so you don’t hear the speaker. It is also possible to set the speaker volume higher, if you want to hear the speaker better than the default low volume setting.
Answer on Xth ring: This option is used when the modem is sharing a line and you only want it to answer after a specified number of rings. For example, the COM220 is sharing a line with people at an office. It can be programmed to only answer after the third ring. If the PC calls when the office is closed and no one answers the phone after three rings, the datalogger will pick it up.
Change telephone system types: Change from the Bell 212A (U.S. and Canada) system to a CCITT V.32 (foreign, 9600 baud) or CCITT V.22 (foreign, 1200 baud) system. This does not mean that the COM220 is tested and approved for all foreign countries.
CITT is an international consultative committee that sets international communications usage standards. V.32 and V.22 are CCITT standards that the COM220 meets.
5. Troubleshooting
When the Campbell Scientific software cannot establish a link to a remote datalogger that is connected to a COM220, check the following:
1)Verify that the modem initialization settings on your computer are correct for your specific calling modem (i.e., the modem attached to your computer). See the calling modem’s software manual and/or help screens for more information.
2)If using a
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