11.8.5 Connecting an analog gauge or source (4-20mA) to the
modem’s analog input:
Figure 28
Follow the above diagram to convert a 4-20mA source into a 0-5Vdc input to the modem’s
analog input (ADC). 249 and 255 ohms are standard values for a 1% resistor.
Readings:
•
At 20mA, the modem reads around 5V on the analog pin
•
At 4mA, the modem reads around 1V
•
When the current loop is missing, the modem reads 0V
11.9 Mounting the modem
The modem requires four #4 screws (3/16”) pan or fillister head, as well as corresponding lock
washers.
