- Four 24-bit quadrature encoder inputs
- Four 16-bit analog outputs
- Eight 16-bit analog inputs
- Eight digital I/O
- Single supply (5 V) input power
- Programmable interrupt timer
- Versatile watchdog timer
- xPC Target Real-time rapid prototyping software available through MathWorks
Model 526 is a versatile analog and digital I/O system on a PC/104 board. It has eight digital I/Os with edge detection, eight 16-bit analog inputs, four 16-bit analog outputs, four counter/timers that can directly interface to incremental encoders, an interrupt timer, and a watchdog timer. The board's high performance, compact size, and diverse resources make it ideally suited for a wide range of measurement and control applications.
The index and quadrature clock inputs accept both differential RS-422 or single-ended TTL/CMOS signals. When connected to an incremental encoder, the count resolution can be increased by selecting a x2 or x4 clock multiplier. Each counter can be programmed to cause an interrupt upon overflow. Counters can be configured as timers by selecting the board's internal clock (27 or 13.5 MHz). Timers can generate and output a "one-shot" pulse or a pulse-width-modulated waveform on one of the digital outputs.
When the watchdog timer is enabled, it will time-out after a selected interval if it is not tagged. Upon time-out, the watchdog timer will activate two external solid state relays, one normally closed and one normally open.
This timer provides a way of generating precise interrupts. Two operating modes are available: manual and auto-restart. In the manual mode, counting starts in response to a software command and stops when zero counts are reached. In Auto-restart mode the counter automatically reloads after zero counts are reached.
Each of the four 16-bit digital-to-analog converters (DACs) has independent preload buffers. A single command will update all DACs in about 32 uS. An interrupt can optionally be generated when the upload is complete. The board employs fully electronic calibration, and all boards are factory calibrated by storing calibration data in on-board, non-volatile memory.
The eight differential inputs are multiplexed to a 16-bit A/D. Multiple channels can be measured in response to a single command. Two reference channels (0 V and 10 V) can also be measured. The A/D converter is factory calibrated by storing the actual value of the on-board 10 V reference in the EEPROM.
Eight I/O lines are available for use as general purpose inputs or outputs in groups of four. Interrupts can be generated on the rising or falling edge of every signal in both groups.
A single 5 VDC power source is required. An on-board DC/DC converter generates all internal operating voltages.
||4, 24-bit synchronous up/down with preload, interrupts
||clockA, clockB, index
Differential RS-422 or single-ended 5 V TTL/CMOS
|Encoder count rate
||10 MHz at 1x
5 MHz at 2x
2.5 MHz at 4x
|Interrupt timer interval
||100 µs to 25.5 ms
||0.125 to 16 seconds
||8 lines with outputs connected to inputs
|Output drive current
|Output sink current
|Input pullup resistor
||State change 0 to 1, 1 to 0
||8 fully differential
||10 kHz one channel
||2 sigma = 4 counts
|D/A driver noise
||2 sigma = 4 counts
|D/A driver current
||5 V, 280 mA