11.8.4 Connecting an analog gauge or source (0-5Vdc) to the
modem’s analog input:
Figure 27
1. Connect the negative side of the analog source to GND.
2. Connect the positive side of the analog source (0VDC - 5VDC) to one of the 2 digital
inputs.
3. These analog inputs are not designed to detect a signal at high speed. This approach
was adopted to minimize the errors which could be caused by the noise of high
frequencies captured by wiring. The detection of a DC source with a slow variation will
not cause any problems.