Each SCM5B43 general purpose input module provides a single channel of transducer input which is filtered, isolated, scaled, and converted to a high-level analog voltage output. This voltage output is logic switch controlled, which allows these modules to share a common analog bus without the requirement of external multiplexers.
The SCM5B43 general purpose input module is designed with a completely isolated computer side circuit which can be floated to ±50V from Power Common, pin 16. This complete isolation means that no connection is required between I/O Common and Power Common for proper operation of the output switch. If desired, the output switch can be turned on continuously by simply connecting pin 22, the Read-Enable pin, to I/O Common, pin 19.
The SCM5B43 general purpose input module can interface to devices which require a precision 10V DC excitation supply. The 1kHz bandwidth significantly reduces ripple and noise inherent in these devices.
Transducer excitation is provided from the SCM5B43 general purpose input module by a very stable 10V source. The excitation supply is fully isolated, allowing the amplifier inputs to operate over the full range of the excitation voltage. This feature offers significant flexibility in real world applications. Eight full scale input ranges are provided, from ±1V to ±10V, producing ±5V full scale output.
The input signal on the SCM5B43 general purpose input module is processed through a pre-amplifier on the field side of the isolation barrier. This pre-amplifier has a gain-bandwidth product of 5MHz and is bandwidth limited to 1kHz. After amplification, the input signal is chopped by a proprietary chopper circuit. Isolation is provided by transformer coupling, again using a proprietary technique to suppress transmission of common mode spikes or surges. The SCM5B43 general purpose input module is powered from +5V DC, ±5%.
Special input circuits on the SCM5B43 general purpose input module provide protection of the signal inputs and the isolated excitation supply up to 240V AC.
