Windmill 752-RTD - RTD Monitoring and ControlThis package comprises Windmill software, a data acquisition and control unit which plugs into the PC's USB port and screw terminal connections. The 752 USB unit provides differential inputs to monitor RTDs, Pt100 probes and voltage signals. You can connect 8 USB units to 1 PC. 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.
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Features
- Monitor RTDs (resistance temperature devices or detectors), PRTs (platinum resistance thermometers), Pt100 probes and voltage signals
- Switch digital outputs
- Monitor digital inputs
- Count events
- Control voltage and current outputs
- 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
- Portable, laptop, desktop and networked data acquisition
- Comprehensive User Manual
- Free technical support for life
What is the USB?
USB, or universal serial bus, ports are found on most new computers. As well as using the USB port for temperature measurement, you can connect peripherals like printers, scanners, digital cameras and telephones. You can unplug USB devices then plug them back as you wish, with no need to restart Windows inbetween.
Temperature Measurement
When the resistance to be measured is small, the resistance in the leads to the RTD can significantly affect accuracy. To address this the 752 unit has a constant current source of 1 milliamp. This gives excellent results for all wiring configurations, including 2 wire, 3 wire, 4 wire and 4 wire compensated. The most accurate results are obtained using a 4 wire arrangement. The current flows through the RTD and the voltage drop over the RTD is measured. Using Ohms law the value of the resistance of the RTD can be calculated, which Windmill software does automatically. The software has linearisation built in for Pt100 probes. For more general information on computerised RTD measurement, see our corporate site.
Digital Inputs and Outputs
The 752-RTD 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.
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.
Screw Terminals
To let you permanently wire your RTDs, we include a screw terminal box. This can also provide extra facilities such as protection from high voltages, output protection and programmable resistance.
Software
Windmill software is included in the 752-RTD package. This modular suite offers data logging, charting, alarm indication, output control and DDE links to other applications like Excel. You can also add process mimic generators, sequence control and many other modules. Should you wish to program the hardware yourself, you can use the IML Tools to do so.
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 RTD 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
Ordering
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