COM220 Telephone Modem
DIFF | AG H L | AG H L AG H L AG E3 AG G G | G G G G 12V 12V | G 12V | SERIAL I/O |
SE | 7 4 8 | 9 5 10 11 6 12 | SWITCHED | POWER |
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| 12V | IN |
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| CAMPBELL |
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| CR10 | |
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| SCIENTIFIC |
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| INC. |
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| MADE IN USA | |
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| SWITCHED | WIRING PANEL NO. | ||
SE | 1 1 2 | 3 2 4 | 5 3 6 | EARTH |
| 12V |
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| CONTROL |
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DIFF | AG H L | AG H L AG H L AG E1 E2 G G |
| G | 5V 5V P1 P2 C8 C7 C6 C5 C4 C3 C2 C1 | |||||
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To Earth
GroundRed 
Black (+12v)
(Ground)
14 AWG Ground Wire 
SC12 Cable
Telephone Wall
Jack
FIGURE 4. CR10X with CR10 Wiring Panel and COM220 Using RJ11C Telephone Jack
4. Modem Settings
The COM220 comes from the factory with the appropriate settings for PakBus dataloggers (e.g., CR8x0, CR1000, CR3000, CR10XPB, CR23XPB). It is programmed to answer a call as soon as a call is detected. It is also programmed for Synchronous Device Communication (SDC7). As mentioned in the introduction, these settings must be modified in order to connect to older dataloggers (e.g. CR510, CR10X, CR23X, CR7) with
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