32-channel digital data acquisition card acquires at up to 720-Mbit/s

February 25, 2016 // By Paul Buckley
Spectrum is claiming a performance breakthrough for the company's M4i.77xx series of Digital Data Acquisition cards for test engineers who require high-speed digital data logging with multi-channel logic analysis over extended time periods.

Based on Spectrum's proven M4i series PCI Express (PCIe) platform the cards are small and compact. Each card comes equipped with 32 fully synchronous channels, large 4 GB on-board memory and a PCI Express x8 Gen 2 interface that offers outstanding data streaming performance. If more channels are needed, up to eight cards can be linked together with Spectrum's Star-Hub clock and trigger distribution system that fully synchronizes up to 256 channels.

Five different models are available with two offering differential inputs, for LVDS, (LV)PECL, (N)ECL and other differential signals, and three models with single-ended inputs for logic levels of 1.2, 1.5, 1.8, 2.5, 3.3, and 5.0 V. The cards are equipped with two VHDCI connectors for the digital channels as well as for the external trigger, clock input and clock output. The connectors also provide two separate multi-function inputs/outputs that can be individually programmed to perform different operations such as trigger out, status output (armed, triggered, ready, etc.) as well as providing additional asynchronous I/O lines.

Top of the range for the single-ended cards is the model M4i.7730-x8 that offers an internal data rate of 720 MBit/s. Other models are available with 125 and 250 MBit/s performance. For the models with differential inputs, the M4i.7735-x8 also boasts an internal data rate of 720 MBit/s while the more economical M4i.7725-x8 offers 250 MBit/s performance.

Using a PCI Express x8 Gen 2 interface means that all of the cards offer ultra-fast data transfer. The interface, together with Spectrum's optimized drivers, enables transfer rates in excess of 3.0 GB/s. So, even at the highest possible sampling rates, all of the channels can be continuously recorded. Streaming the acquired waveforms to PC-based storage systems,  such as Spectrum's Tera-store units, even allows the uninterrupted recording of data for minutes or hours at a time.

The fast transfer speed of the cards is complimented by a variety of acquisition modes that include single-shot, multiple recording, gated sampling and continuous streaming (FIFO). These acquisition modes are further supported by a flexible trigger engine that allows full pattern triggering, together with trigger time stamping.

For state analysis, an external clock can be used to synchronously sample the applied data. In this mode, the clock is allowed to have gaps, as long as the minimum required high and low times are satisfied. To simplify the synchronous sampling of the data, the incoming clock signal can also be time shifted or delayed with respect to the data, to ensure correct data capture.