ADLINK DAQ/DAQE/PXI-220x acquisition card fully configured

ADLINK DAQ/DAQE/PXI-220x Series Acquisition Card Configuration and Calibration

In the fields of high-precision multi-channel data acquisition, automated testing, and process monitoring, ADLINK's DAQ/DAQE/PXI-220x series high-performance multifunctional data acquisition cards have become an ideal choice for engineers to build complex measurement and control systems due to their flexible channel configuration, rich trigger modes, efficient DMA transfer, and synchronization capabilities. This series covers three bus specifications: DAQ (PCI), DAQE (PCIe), and PXI, including models 2204 (12 bit/3MS/s), 2205 (16 bit/500kS/s), 2206 (16 bit/250kS/s), and 2208 (96 channel/12 bit/3MS/s, without dual DA and GPTC). This article will provide you with a complete technical guide from hardware configuration, analog input/output, timer/counter, triggering and synchronization, calibration, and software ecology dimensions, from selection to in-depth application.

Analog input: channel, gain and input mode

The 220x series supports mixed configurations of single ended (SE) and differential (DI) inputs, and the software can be set channel by channel. Among them, 2204/2205/2206 provides 64 SE or 32 DI channels, while 2208 extends to 96 SE or 48 DI channels. Each channel can independently choose bipolar (± 10V, ± 5V, ± 2.5V, ± 1.25V, etc.) or unipolar (0~10V, 0~5V, 0~2.5V, 0~1.25V), and the gain range varies by model: 2204/2208 supports up to 10 levels of gain (× 1~× 200), while 2205/2206 provides × 1, × 2, × 4, × 8.

Key performance indicators (excerpted from the manual):

System noise: 2205 has a typical value of only 0.95 LSB rms in the ± 10V range, while 2206 has a lower value of 0.8 LSB rms.

CMRR: In differential mode, the ± 5V range can reach 90dB (DC~60Hz), effectively suppressing power frequency interference.

Input impedance: 1G Ω//100pF when powered on, suitable for high impedance signal sources; Overvoltage protection up to ± 30V (power on) and ± 15V (power off).

Practical input signal connection:

Floating ground signal (such as thermocouple): using RSE (Reference Single End) mode, the board provides ground reference; In differential mode, a resistor (approximately 100 times the source impedance) needs to be added between AIL and AIGND to provide a bias circuit.

Grounding reference signal (such as non isolated output): NRSE (non reference single ended) mode is recommended, where the signal is locally grounded to AISENSE and the common mode rejection of the instrument amplifier is used to eliminate the ground potential difference; Differential mode can also be used to directly connect AIH/AIL.

The channel gain queue (up to 512/1024 words) allows users to freely arrange the scanning order, with each entry specifying the channel number, range, and input type. For example, if the queue is set to ch1 (± 10V), ch2 (± 2.5V DIFF), and ch0 (0-5V), the sampling order will cycle in this way, greatly simplifying the mixed acquisition of multiple types of signals.

Scanning acquisition and triggering mode: precise timing and event synchronization

To obtain a fixed and accurate sampling rate, a programmable scanning acquisition mode must be used, whose core timing is controlled by the following counters:

SI_comounter (24 bits): Scan interval=SI_comounter/Timebase (internal 40MHz or external 1-40MHz).

SI2-Counter (16 bits): Channel sampling interval=SI2-Counter/Timebase.

NumChan_comounter (9 bits): The number of samples per scan (i.e. channel gain queue length).

PSC_counter (24 bits): The number of scans collected after triggering.

M6ounter (16 bits): The number of scans stored before triggering in the pre trigger/mid trigger.

Temporal constraint: SI_comount ≥ SI2-Count × NumChan_comount, and the maximum sampling rate is limited by the model (2204/2208 is 3MS/s for single channel, 1MS/s for multiple channels; 2205 is 500kS/s; 2206 is 250kS/s. For example, when using internal 40MHz in 2204, the minimum SI2 is 14 (≈ 2.86 μ s/point).

Five triggering modes:

Software trigger: Start immediately, suitable for simple applications.

Post trigger: Collect PSC_counter scans after triggering.

Delay trigger: After triggering, the data is collected with a delay of Delay_counter clock cycles. The delay clock can be either Timebase or sampling clock.

Pre trigger: Continuously collect data before triggering, stop after triggering, and only retain the last M-counter scans. The 'enable' bit can forcibly ignore premature triggering to ensure a complete M-scan.

Middle trigger: Collect M-scan before triggering and N-scan after triggering (PSC_counter=N), also supporting M-enable.

Engineering Tip: In pre trigger and mid trigger modes, if the trigger occurs in the middle of the scan, the current scan will be completed before stopping to ensure that the data is aligned with the complete scan. The Re trigger function can be triggered multiple times in post/delay mode, with a fixed number of scans collected each time, making it very suitable for recording sudden signals.

DMA data transfer and high-performance continuous acquisition

High speed data acquisition must rely on bus master DMA. This card supports DMA with scatter/gather function, which can link multiple discontinuous memory blocks into a linked list, breaking through the limitation of continuous large memory allocation. The maximum transfer volume is only limited by system memory and PCI bandwidth. After DMA startup, the hardware automatically moves FIFO data to the host, with almost zero CPU load. The sampling rate of 2204/2208 is as high as 3MS/s, and the FIFO has 1024 samples. If not DMA transferred in time, it is prone to overflow.