The Sigmatronics AIDIO module is an interface to allow standard 4-20mA current loop process signals to be easily, safely, and conveniently attached to a PC based data acquisition system.

The module provides independent isolation between each input channel and the rest of the system.  This reduces noise pick-up and also eliminates interfacing problems associated with grounded devices.  The AIDIO's inputs can be placed anywhere in the loop, and need not be referenced to ground or the positive side of the loop.  This lets you use your PC data acquisition system along with other current loop instruments which may require a ground side connection.

Along with the extremely rugged and forgiving input protection circuits, each channel also includes two input fuses.  The standard, and most commonly available fuse type (1/4" X 1 1/4") was chosen to make field replacement easy.  The energy limiting built into the protection circuits eliminates fuse blowing in all but the most severe overload conditions.  This reduces unnecessary "repair" calls.  No AIDIO circuit has ever needed repair in the seven years that these circuits have been in use in the field.  The only fuse replacements we've ever needed to perform have occurred after lightning strikes which actually caused nearby power poles to catch fire.

In addition to eight channels of current loop analog inputs, the AIDIO can also provide six channels of digital contact-sensing inputs.  These are usually configured as three contact sensors and three counter-timer inputs.

For control of outside devices, the module also provides four SPDT dry contact relay outputs.  Each contact is capable of handling 5 Amps at 120 VAC.

The AIDIO is designed to interface with popular analog ISA/PCI bus interface cards from several manufacturers.

The AIDIO connects to these cards with a 37 pin cable and acts as the interface and protection between the real-world end devices and the sensitive PC and its data acquisition board(s).