This package comprises Windmill software, the 752 measurement and control unit which plugs into the PC's USB port, and free, lifetime, technical support. The 752 unit provides differential inputs to monitor resistance and voltage signals. The units also provide digital input and output, counting, and voltage or current output control. The system supports 2 wire, 3 wire, 4 wire and 4 wire compensated resistance measurement. With extra hardware you can also monitor thermocouples and strain gauge bridges.
Price: 895 GB pounds.

Features

• Monitor resistance and voltage signals
• Switch digital outputs
• Monitor digital inputs
• Count events
• With extra hardware monitor thermocouples and strain gauge bridges
• Control voltage or current outputs
• Supports 2 wire, 3 wire, 4 wire and 4 wire compensated resistance measurement
• Includes the powerful yet easy-to-use Windmill software for Windows: no programming required
• Connect up to 8 USB units to one PC
• Choice of analogue input ranges, selected with Windmill software individually for each channel
• Alternatively, choose automatic ranging and let the software match the input signal as closely as possible
• Integrating analogue-to-digital converter reduces electrical noise
• Use Windmill to select the resolution of the A-D converter from 12- to 18-bits
• Automatic recalibration
• Comprehensive User Manual
• Free technical support for life

Resistance and Voltage Measurement

Resistance measurements are made by passing a constant, known, current through the unknown resistance, and monitoring the voltage drop across the resistance. The 752 unit has a constant current source of 1 milliamp.

When the resistance to be measured is small, the resistance in the leads to the sensors can significantly affect accuracy. However, different wiring configurations allow the lead resistance to be measured and compensated for. The Microlink 752 gives excellent results for all configurations, including 2 wire, 3 wire, 4 wire and 4 wire compensated. The most accurate results are obtained using a 4 wire arrangement. More connections are required for these arrangements than for straightforward voltage measurement. This means that you can monitor 16 voltages or 8 resistances, or a combination of the two such as 8 voltages and 4 resistances.

Digital Inputs and Outputs

The Microlink 752 provides 24 digital I/O lines, arranged in three 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 USB unit has eight 16-bit totalling counters. Each counter starts at zero and counts pulses to a maximum of 65535. 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.

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.

Thermocouples and Strain Gauges

By adding a Microlink 593 unit, which provides cold junction measurement, you can also monitor thermocouples. For strain gauges you need a Microlink 594 connection box and excitation supply.

Software

Windmill Charting software

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

USB Unit Specifications

 Dimensions (mm)             180 x 120 x 40
 Maximum length of cable     5 m
 Maximum distance from PC can be increased by 
 use of USB hubs
ANALOGUE INPUTS
 Current source            1 milliampere
 Maximum resistance inputs 8
 Maximum voltage inputs    16
Maximum safe input voltage:
 Power supply on           ±48 V
 Power supply off          ±33 V
 Transient                 ±300 V
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
ANALOGUE OUTPUTS
 Voltage output            0-10.240 V
 Max # voltage outputs     2
 Current output            0-20.480 mA
 Max # current outputs     2
 Resolution                12 bits
DIGITAL INPUTS/OUTPUTS
 Maximum number inputs     24
 Maximum number outputs    24
 (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 number counters   8
 Resolution                16 bits
 Compatibility             TTL, 5 V CMOS, can be made
 contact closure compatible
 Input voltage range       0 to 5 V
 Maximum count speed       160 counts per second