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39 PCIE-1816_1816H User Manual
Appendix B
O
peration
Theory
B.1.2 Analog Input Ranges and Gains
The PCIE-1816/1816H can measure both unipolar and bipolar analog input signals.
A unipolar signal can range from 0 to 10 V FSR (Full Scale Range), while a bipolar
signal extends within ±10 V FSR. The PCIE-1816/1816H provides various program-
mable gain levels and each channel is allowed to set its own input range individually.
Table B.1 lists the effective ranges supported by the PCIE-1816/1816H with gains.
For each channel, choose the gain level providing the most optimal range that can
accommodate the signal range you want to measure.
B.1.3 Analog Input Acquisition Mode
The PCIE-1816/1816H can acquire data in either single value or pacer mode.
 Single Value Acquisition (Polling) Mode
The single value acquisition mode is the simplest way to acquire data. User can sim-
ply poll the data register of the desired channel to get the latest acquired value. Each
analog input channel has its own dedicated data register (buffer) and in this mode the
PCIE-1816/1816H updates each channel cyclically. The update rate is sampling rate/
num. of active channels.
 Buffer Mode
Adopt buffer mode to acquire data if you wanna accurately control the time interval
between conversions. AI conversion clocks come from internal clock sources or
external signals on connector. AI conversion starts when the clocks signal come in,
and will not stop if the clocks are continuously sent. Conversion data is accumulated
into the on-board AI buffer and waiting the transfer to PC memory. Further, you can
specify Trigger to acquire the desired periods. We will discuss the detail in the next
sections.
 AI Data Acquisition Clock Timing
The PCIE-1816/1816H introduces a double-clock system, with SCAN clock and
CONV clock, to generate efficient AI conversion clocks at dedicated timing. You can
control acquisition timing interval precisely and just acquire the desired period. It can
save the waste of PCI bandwidth with continuing acquisition and post data process-
ing by filtering-out the redundant data beforehand. In this section, we will describe
how it works and its timing reference in detail.
Table B.1: Gains and Analog Input Range
Gain Unipolar Analog Input Range Bipolar Analog Input Range
0.5 N/A ±10 V
1 0 ~ 10 V ±5 V
2 0 ~ 5 V ±2.5 V
4 0 ~ 2.5 V ±1.25 V
8 0 ~ 1.25 V ±0.625 V