APD 7500 Series DC to Frequency Transmitters

The APD 7500 accepts a DC voltage or current input and provides an optically isolated frequency output that is directly proportional to the input. Common applications include pulse counting or totalizing of DC process signals from devices such as flow transmitters, analog signal transmission over long distances, or analog inputs into PLCs. The full 3-way (input, output, power) isolation makes this module useful for ground loop elimination, common mode signal rejection or noise pickup reduction.

A low frequency cutout potentiometer can be adjusted to disable the output when the input falls below a pre-determined level. The APD 7500 can be field-configured via external rotary and slide switches. Common ranges are on the module label, however, virtually unlimited combinations are possible.

The APD 7500 has an open drain MOSFET (open collector) output which requires a user supplied external power supply and pull-up resistor allowing the module to be interfaced with a wide variety of devices. To convert the output to a powered TTL output, simply jumper terminals 1 and 2.