|Model 626 | Multifunction Analog/Digital I/O|
Model 626 is a PCI board that saves space and reduces cost by combining several popular interface functions on a half-size card. It has six versatile 24-bit counters that support incremental encoders as well as single-clock sources, 48 bidirectional digital I/Os (40 with edge detection), sixteen differential analog inputs, four analog outputs, and a watchdog timer. Five low profile connectors are used with optional flat cables to connect the board to external breakout boards.
Encoders and Counters
Three 24-bit up/down counter pairs may be configured for six incremental encoders, each having 24-bits of resolution. Each channel accepts two phased TTL or RS-422 signals plus an index signal to track encoder direction and displacement. Each input is conditioned and synchronized to the 626’s internal clock.
Unlike conventional counters, the 626’s counters do not accumulate errors when the encoder dithers or changes direction. The 626 supplies 5 volt power to each encoder channel. All counters are programmable and may optionally generate interrupts.
The counter channels have a battery backup feature that keeps them running during a power failure. The 626’s battery charger will recharge an external 3.6V NiCd when power is restored.
Each counter can function as a timer using the board's internal clock or an external clock. When paired, 48-bit counters may be used for frequency measurement.
Sixteen differential input channels are multiplexed to a sample/hold and successive approximation A/D. Each channel may be programmed for ± 5V or ± 10V. No trim adjustments are needed.
Four voltage outputs may be programmed for ± 10 volts. A unique circuit prevents unpredictable D/A outputs during CPU initialization. All outputs are reset to zero volts whenever a bus reset occurs.
The board's watchdog timer may be connected to the bus reset via a 2-pin connector. It may be enabled or disabled under program control. The timer is automatically disabled whenever a bus reset occurs. A mechanical relay is provided to signal external circuitry. The relay can be activated by the watchdog timer or under software control.
Fail-safe Digital I/O
In the event that power is lost to the PC, solid state relays connected to the 626’s digital I/O will not be powered to the on state. This allows solid state relay boards to be powered from a remote power supply without the chance of output relays turning on when the PC is turned off.
The board's 48 digital lines have standard pinouts for solid state relay boards. Each line is software programmable as an input or output. 40 of the inputs may be independently programmed for edge detection. All outputs are turned off upon system reset.