The 851-SG package comprises Windmill data acquisition and control software, a data logger to monitor 16 strain gauges and strain gauge excitation.
Price: 875 GB pounds.

Features

• Monitor strain gauges, pressure transducers or voltage signals, through 16 differential input channels
• Can also monitor digital inputs, count, control digital outputs and measure temperature, pressure, flow, level, etc (extra hardware may be needed)
• Read data over an Ethernet network or over the Internet
• Includes the powerful yet easy-to-use Windmill Software for Windows: no programming required
• Automatic ranging lets the software match the strain signal as closely as possible
• Integrating analogue-to-digital converter reduces electrical noise
• Use software to select the resolution of the A-D converter from 12- to 18-bits: choose between high resolution and high speed
• Automatic recalibration
• Set two alarms on each strain gauge
• Measurements returned in microstrain, or engineering units of your choice
• Use for real-time data acquisition on your PC or for stand-alone data logging
• Free technical support for life and money-back guarantee if not satisfied

Strain Measurement

The 851-SG package comprises an 851 data logger, a strain connection box and Windmill data acquisition software. Just connect your strain gauges to the strain box, plug the box into the 851 Data Logger and away you go. This method of connection means you can use the 851 Data Logger to monitor, for example, temperature at the same time as strain.

With the 851-SG package you can monitor strain gauge bridges and balanced bridges such as pressure transducers. You can configure individual channels to accept any of these inputs:

• voltage
• quarter bridge: single strain gauge
• half bridge: tensile + compressive strain gauge
• half bridge: normal + transverse strain gauge
• full bridge: 2 tensile + 2 compressive gauges
• full bridge: 2 normal + 2 transverse gauges
• full bridge: tensile normal + compressive normal + tensile transverse + compressive transverse gauge

Strain gauges need an external excitation voltage to supply sufficient current to keep all the bridge circuits energised. The 851-SG package provides four sets of 16 screw terminals giving + and - excitation and signals for each of 16 bridges. Two 1 kOhm termination resistors are mounted in half bridge configuration whilst high quality 350 and 120 Ohm resistors can be provided for the completion of quarter bridges.

When a bridge input is selected the Windmill software monitors excitation voltage and performs the bridge calculation to produce a reading in microstrain. This eliminates errors due to changes in excitation voltage.

The initial unstrained bridge measurement is often much larger than the change in signal due to strain. If this initial value is not accounted for, it restricts the resolution you can obtain - i.e. the smallest signal you can measure. Windmill software can zero or balance the bridge, nulling the offset of the initial voltage. So instead of measuring over a wide range, 0 to 0.5 V for example, you can choose a narrow range such as 0 to 0.01 V.

Each range is divided into a fixed number of steps: the resolution. The smaller the range and the larger the resolution, the more precise the reading. The 851-SG offers a choice of resolutions from 12-bit for fast sampling to 18-bit for greater precision.

Set Alarms on Each Strain Gauge

You can set two alarm levels on each strain gauge and specify what happens when an alarm threshold is crossed, for example other equipment could be switched on.

Digital Inputs and Outputs

The 851-SG provides 32 digital I/O lines, arranged in four groups of 8. Use Windmill to choose whether each group is an input or an output. You can read or set the state of each line individually. Alternatively, you can switch several channels at the same time.

Counters

The unit has eight 23-bit totalling counters. Each counter starts at zero and counts pulses to a maximum of 1 million. You can reset a counter at any time from Windmill software. You can use the counters in two modes: accumulating count and resetting count. In accumulating count the counter keeps counting until you reset it. In resetting count the counter shows the number of pulses since the last reading.

You can set a scale and offset factor to the count from software. For example if the pulses came from a flow meter which produced one pulse for every 50 millilitres, a scale factor of 0.05 would give a reading in litres.

The counters are found on 8 of the digital input and output lines. You can use any of these you don't need for counting as normal digital inputs: the counts are always maintained even if you don't plan to use them.

Software

Windmill Software is included in the 851-sg package. This modular suite offers data logging, charting, alarm indication, output control, process mimic generators, sequence control, programming tools and other applications.

Free Technical Support and Money-Back Guarantee

All our systems come with free technical support for life and a guarantee that if you aren't satisfied we'll give you your money back.

Specifications

 Dimensions (mm)           180 x 120 x 40
 Maximum logging speed     10 scans a second
 Memory                    65000 scans
SOFTWARE
 Operating system          Windows 10, 8, 7 64-bit, 7 32-bit
 Vista, XP, 2000 or 98
ANALOGUE INPUTS
 Maximum # inputs          16 differential
Maximum safe input voltage:
 Power supply on           ±48 V
 Power supply off          ±33 V
 Transient                 ±300 V
Amplifier:
 Ranges (V)                ±0.01, ±0.1, ±1, ±10
 Common mode range         ±13 V
 Relative accuracy of ranges:
 gain = 1000               ±0.1%
 gain = 1, 10, 100         ±0.05%
Analogue to Digital Converter:
 Maximum linearity error   ±0.02%
 Resolution    Integration Time    Samples/Second
 12 bits         2.5 msec          80
 13 bits         5 msec            64
 14 bits        10 msec            48
 15 bits        20 msec            32
 16 bits        40 msec            16
 18 bits       160 msec             6
DIGITAL INPUTS/OUTPUTS
 Maximum # inputs          32
 Maximum # outputs         32
 (selected through Windmill in ports of 8 lines)
 Power-up state            all inputs
 Compatibility             TTL and 5 V CMOS, can be made 
 contact closure compatible
 Range                     0 to 5 V
 Output capability         15 LSTLL loads
 Maximum I/O speed         160 channels per second
COUNTERS
 Maximum # counters        8
 Resolution                23 bits
 Maximum count (events)    1000000
 Maximum frequency         5 kHz
 Minimum pulse width        500 µseconds
 Frequency gate times      1 or 10 seconds
 Compatibility             TTL, 5 V CMOS, can be made
 contact closure compatible
 Input voltage range       0 to 5 V