I/O Board’s Features Reduce Processor Overhead

The Model 104-DIO-48S, a 48-bit parallel digital input/output card designed for PC/104-based data acquisition, incorporates change-of-state detection on selected ports. This allows the card to generate interrupts port by port, and since one READ determines the data, there is no need for constant polling. The board contains two 82C-55A Programmable Peripheral Interface chips (PPI) to provide a computer interface to the 48 I/O lines. Each PPI provides two 8-bit ports on A and B and two 4-bit ports on C. Each port can be software configured to function as either inputs or latched outputs. Each I/O line is buffered and capable of sourcing 15 mA or sinking 24 mA. For contact monitoring, the board includes pull-ups to 5V. The 104-DIO-48S uses two industry-standard 50-pin headers on the face of the board, plus one 10-pin header for the optional counter timer. Included is a 1 MHz on-board clock and three 16-bit down counters that configure for event counters, frequency measurement or generating frequency or pulse outputs. Other features include: a power requirement of +5V at 200 mA, maximum; an operating temperature range of 0_C to 65_C (-40_C to +85_C optional); and compatibility with Opto-22 and other industry standard I/O racks. Pricing ranges from $145 (base model card, no counter/timers or change-of-state detection) to $190 (includes one 82C54 counter and change-of-state detection). ACCES I/O PRODUCTS INC., San Diego, CA. (858) 550-9559.