Spectrum Controls 1769 User Manual page 13

Chapter 1: Module Overview 1-5
From the readings taken by the converter, the module returns an accurate temperature or
resistance to the controller user program through the microprocessor. The module uses
two bidirectional serial ports for communication, each using an optocoupler for isolation.
A third optocoupler is used to reset the microprocessor if the module detects a loss of
communication.
User's Manual Pub. 0300241-01 Rev. A