7220 Description
The Model 7220 is a high-performance, high-accuracy voltage
scanner and member of the 7200 series of ruggedized
measurement systems. A network appliance, it provides input
sensitivities from 10 millivolts to 10 Volts full scale. The
rugged enclosure is designed for installation in wind tunnels,
engine test stands and other facilities where it is desired to
locate the data acquisition close to the test article reducing
installation and cable cost and improving signal quality and
reliability.
Fully self-contained the 7220 provides regulated power for
transducers that have built-in electronics. The transducer
power is programmable from 0 to 15 Volts. The input signals
are amplified, filtered to remove signal components that could
produce alias errors and digitized to 24-bit resolution. The
digitized signals are digitally processed providing multiple
sample rates, 80 dB/octave FIR filters and 32-bit floating point
outputs in millivolts referred to input, millivolts referred to
output or user defined engineering units.
The inputs are digitized, processed and output at 10 to 24,000
samples per second as selected for individual channels. A digital
signal processor (DSP) provides low-pass filtering selectable
from 10 Hz to 3,000 Hz with 80 db/octave attenuation. The
DSP can be custom programmed to provide alternate filter
responses and perform application specific signal processing.
Each 7220 has a 100BaseT Ethernet interface for control and
data output, which simplifies system wiring and provides
remote and distributed operation. IRIG time may be employed
to synchronize sampling on multiple units within 10
microseconds or a timing pulse may be used to achieve better
than 1 microsecond time alignment. Multiple Bricks with up
to 4,096 channels may be connected on a single Ethernet
LAN.
The case features interchangeable end plates that provide fully
sealed, ambient air or forced air cooling. Forced air cooling
provides the capability to operate over a wide temperature
range according to application requirements. Occupying less
than 500 cubic inches and weighing less than 14 pounds the
7220 can be installed in locations previously not suitable for
data acquisition systems. The Ethernet interface and IRIG
timing make it easy to distribute units throughout the test
facility minimizing sensor cabling and installation costs.
The Model 7220 does not sacrifice performance. In fact, it
features higher accuracy than most systems designed for a
laboratory environment. That’s because it is self calibrating,
taking into account temperature variations. Accuracy is better
than 0.025% for gains up to 200 and 0.05% for gains above
200 over the temperature range -20°C to +50°C, which can be
extended to higher temperatures by forced air cooling.
Calibration and performance verification is accomplished by
PANEL72 Maintenance and Calibration software. The
ACS2000 Automatic Calibration System automates performance
verification and periodic instrument calibration.
7220 Installation
Locating data acquisition
hardware near transducers at many test facilities has required
specially constructed and environmentally conditioned enclosures.
Using the 7220, the data acquisition can be installed
in unprepared locations and the only external connections are
power, timing and Ethernet.
7220 Accuracy
The 7220 maintains ±0.025% uncertainty (±0.05% for gains
above 200) over the full temperature range by continuously
correcting for temperature induced gain and zero variations. It
is initially calibrated over the full temperature range with gain
and zero correction vectors stored in non-volatile memory. An
internal sensor determines the correction vectors applied to the
data according to the device temperature. Software is
available for automatic recalibration. Voltage calibration, using
an internal precision voltage reference is provided to confirm
accuracy and perform health checks.
7220 Transducer Power
Each channel has an independent, regulated power source that
provides operating power for transducers with internal
electronics. This power source may be programmed for 0 to
+15 Volts output regulated to 0.1%. It can supply up to 50
mA and is current limited so it will not be damaged by a
shorted output.
7220 Instrumentation Amplifier
The inputs are protected up to ±50 Volts differential and
common mode. They are applied to a high-impedance,
programmable gain, differential instrumentation amplifier. The
amplifier has programmable gains from 1 to 1,000 providing
full-scale input ranges of ±10 mV to ±10 Volts. Calibrated
gain steps with ±0.02% accuracy are provided or the amplifier
gain may be continuously programmed. Autozero maintains
the amplifier output offset within ±1 mV.
7220 Analog to Digital
Conditioned and amplified transducer signals are digitized by a
24-bit resolution Sigma-Delta analog-to-digital converter that
over-samples the analog signal enabling the use of a
single-frequency anti-aliasing filter.
7220 Sampling
Sampling is synchronized between channels and systems
providing time aligned data. All channels are simultaneously
sampled at the highest sample rate, 24 kS/s. The sample
rate clock may be synchronized to IRIG A, B or G time. IRIG
G time is generate by the unit connected to the external IRIG
source or designated as the master time source if external
IRIG is not used. Distributed to multiple system it maintains
channel to channel time skew under 10 microseconds for
channels in the same or other units using the same master
time source. Alternatively a TTL Sync input may be used to
maintain time skew of less than 1 microsecond. If the timing
signal is not present or lost during acquisition sampling will
continue at the last programmed rate using an internal clock.
7220 Filter
Finite Impulse Response (FIR) filtering is provided. Eighty
sets of 128 FIR filter coefficients are available in each 7200
providing an extensive selection of filter frequencies and
characteristics. The coefficients are user programmable, and
each coefficient is 18 bits in length. The filters may be
loaded with customer-specified default coefficients providing
logical filter cutoff selections and characteristics. The default
filter frequencies and characteristics are easily changed to
satisfy future requirements.
7220 Data
Data are output on the Ethernet interface. The output data is
32-bit floating point format and can be chosen via programming
to be Volts, millivolts or microvolts referred to input or
output or user defined engineering units derived from a
polynomial expression. Each unit can output data from all
channels at the maximum sample rate. Data rates in excess of
7 million samples per second are achievable from combined
7200 systems on a single LAN.
7220 Programming
All operating parameters can be set and queried using the
extensive, built-in command set. Setup information is saved in
password protected EEPROM memory on board, and it is
automatically restored when power is applied or the system
reset. The command set is well documented, and source code
programming examples are provided.
7220 Calibration & Performance Verification
PANEL72 is Pacific’s maintenance and calibration software. It
may be used to troubleshoot installation problems and calibrate
the 7220. The ACS2000 is an automated calibration system
that performs performance verification, calibration and
accuracy certification to NIST traceable standards.
7220 Communications
Initializing communication with the 7200 is simple. Commands
are included that enumerate the 7200 devices on the network.
After the enumeration operating software creates a socket
interface between itself and each 7200. Simple Send and
Receive network commands are used to communicate. Status
LEDs that assist with initial setup are located on the connector
end of the enclosure. Multiple systems, up to 4,096
channels, may be connected to a single Ethernet LAN.
[Call: 925-827-9010] 
