Measurement Computing DaqTemp - Manual (Page 19)

DaqTemp User’s Manual 09-06-02 Overview & Theory of Operation 1-11
Each DaqTemp makes use of one high-speed, multi-function, PCI plug-and-play data acquisition board. The PCI
board features a 16-bit, 200-kHz A/D converter (ADC), digital calibration, bus mastering DMA, 24 digital I/O lines,
four counters, and two timers. In addition, the DaqTemp7A has two16-bit 100 kHz D/A converters (DACs); and the
DaqTemp14A has four DACs.
DaqTemp modules provide access to all of the system’s input and output signals. A 100-pin connector on each
module connects to a mating connector on the associated PCI board. The connection is made via a CA-195, 100-
conductor ribbon cable.
Signal types applicable to the DaqTemps are:
• Analog Input: 7 differential analog inputs with 13 software programmable ranges
(±10 V to ±156 mV full scale).
• General purpose: 24 lines for Digital I/O.
• 4 Counter Inputs, 2 Timer Outputs
• 2 Analog Outputs for DaqTemp7A
• 4 Analog Outputs for DaqTemp14A
• 7 Thermocouple Inputs for DaqTemp7A and DaqTemp7
• 14 Thermocouple Inputs for DaqTemp14A and DaqTemp14
The PCI board’s scan sequencer lets you select up to 512 channel/range combinations. The sequencer scans all
channels of the scan at 5
µs per channel, or 10 µs per channel.
Bus mastering allows analog and digital/counter input data, as well as analog and digital output data, to flow between
the PC and the DaqTemp without consuming CPU time.
DaqTemps support a full complement of trigger modes including:
• Hardware analog triggering – A user-programmed trigger level sets an analog DAC, which is
compared in hardware to the analog input level on the selected channel. Trigger latency is < 5 µs.
• Digital and pattern triggering – The boards have separate digital trigger input line, allowing TTL-level
triggering and latencies less than 5 µs. The trigger can be programmed for logic level or edge triggering.
In pattern triggering, any of the digital input ports acts as the trigger port. You can program the digital
pattern.
• Software-based triggering – The PC detects the trigger event from readings, either analog, digital, or
counter. Six pre- and post-triggering modes are supported.
Additional features:
• 24 TTL-level digital I/O lines. They are divided into three 8-bit ports.
• Four 16-bit counters. Each can accept frequency inputs up to 10 MHz.
The counters can be cascaded into two 32-bit counters.
• Two 16-bit timer outputs. Each can generate square waves from 16 Hz to 1 MHz.
• Configuration through software. The DaqTemp modules and PCI boards have no switches or
jumpers.
• Analog Outputs, DaqTemp7A and DaqTemp14A only. The 16-bit, 100-kHz analog output channels
have an output range of -10 V to +10 V. (These channels are separate from the D/As used to determine
analog trigger levels.) Using Bus Mastering DMA, each D/A can output a waveform. Bus Mastering
DMA also allows for digital pattern generation on the 16-bit high-speed digital I/O port.