Model 104-DA12-8A is a PC104 board featuring eight independent 12-bit digital-to-analog converters (DACs) and broadly configurable arbitrary waveform generation (ARB) capabilities. Other convenient features include 128K SRAM for waveform data storage, eight 4-20mA current sinks, three 16-bit counter/timers and fused general-purpose +5V and +12V power outputs. An economy version is available without the ARB feature as model 104-DA12-8.
The DACs can be updated individually or simultaneously. An automatic circuit sets the analog outputs to zero at power-on or reset. Each output is buffered by a short-circuit protected op-amp capable of sourcing up to 5mA. Data for updating each DAC may come from either the board's onboard RAM or from the PC/104 bus. The on-board 128 KB (64K sample) RAM and onboard intelligent circuitry provides flexible allocation of between one and eight FIFO buffers/waveforms.
Arbitrary waveform generation capability becomes increasingly necessary as CPUs are burdened with a greater abundance of complex tasks. An arbitrary waveform is a user-defined set of digital values specified point by point over time. These values are then clocked through a DAC to provide the analog output signal. Virtually any waveform can be created using the software tools provided by ACCES and also by third-party software packages. The ARB relieves some of the load placed on the CPU by handling the waveform generation at the hardware level using on-board memory and control logic. This is especially useful in time-critical applications as outputs remain unaffected by latencies inherent in popular operating systems. ACCES I/O’s ARB architecture allows for total flexibility in allocating the onboard RAM across the channels depending on the complexity of the desired waveform. It is even possible to use the ARB for selected channels while operating the remaining channels in the software driven mode.