A Smart Transducer Interface Module(STIM) is a module that contains TEDS, logic to implement the transducer interface, the transducer(s) and any signal conversion or signal conditioning. It consists of 1 to 255 sensors or actuators or any combination of them, DAC, ADC and Digital I/O to interface the sensors or actuators. It also consists of conversion circuitry, address logic, and digital electronics or microprocessors to convert the sensor readings into digital form, or to convert digital output to manipulate actuators to and from the network. The address logic facilitates communication between the STIM and an NCAP. Through the NCAP sensor data is passed to a network. When a STIM contains more than one transducer, it may be referred to as a multichannel STIM or a multi variable STIM.
When power is applied to the STIM, the information that it carries in the TEDS is made available to the NCAP for local usage, and for distribution to the rest of the network as necessary. Once the TEDS is read, the NCAP knows how fast it can communicate with the STIM, how many channels the STIM has, and the data format of each channel. It can then send information to the STIM, or ask the sensor to perform a reading or get information about readings from the sensor.
A sensor/actuator STIM can be used for distributed measurement and control
applications. If the STIM has local processing capabilities, it has a microprocessor.
In this case, the NCAP remotely directs the control of a process, which
is locally controlled by the STIM. The STIM uses the sensors to measure
the process variables and parameters. Based on the sensor inputs, preset
control points and control algorithms, the microprocessor sends control
signals to manipulate actuators to a preset value. The STIM then reports
the control status to the NCAP.