Diagnostic Test Circuit for Isolated Digital Inputs
Original Publication Date: 1978-Jun-01
Included in the Prior Art Database: 2005-Feb-21
The Digital Input/Process Interrupts (DI/PI) Isolated Card in the Model 3530 Sensor Input/Output (I/O) unit, used in conjunction with the IBM Series/1 Computer System, requires diagnostic commands to test proper operation of the card. Heretofore, diagnostic circuits for the isolated DI/PI card have not had provision to test any part of the optical isolator. A solution is described which tests part of the isolator while reducing parts count and increasing serviceability by closing the loop more closely to the customer inputs.