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Microlink Measurement and Control Systems

Microlink 3000: Modular Measurement and Control


Microlink 306x - Single Channel Analogue Input Modules

The main benefit to be gained from using the 306x modules is in high speed scanning applications. Your choice of module is held in a Microlink frame, along with an analogue-to-digital converter module.


Microlink 3060 - Analogue Input with RMS

The 3060 provides a differential voltage input with an rms converter, giving the root and mean square value of an AC input signal. It does a similar job to the Microlink 3053, but doesn't have to wait for 200 ms settling time between inputs. It is therefore more suitable for use in high speed scanning systems.

Offset voltage drift (gain=100)     1 uV/oC
Input bias current                  ±30 nA
Common mode rejection (gain=1000)   105 dB
Common mode range                   ±10 V
Frequency response                  50 kHz
Relative accuracy of gain ranges    0.02%
Initial accuracy of gain and offset ±1 LSB
Input noise voltage                 2 uV rms

Microlink 3061 - Analogue Input with Sample and Hold

The 3061 module provides a general purpose differential voltage input. It features a sample and hold circuit for simultaneous sampling in high speed scans. The circuit is activated by a software flag. At the start of each high speed scan all 3061s are placed in hold mode. A conversion is taken from each one and any other analogue inputs in the scan. At the end of the scan the 3061s are returned to sample mode.

The purpose of the sample and hold circuit is to be able to freeze the input signal at a particular moment in time, and hold the value until the A-D converter can complete the conversion. (Note that the 3042 to 3043 A-D converters all feature sample and hold circuits to hold the voltage while the conversion takes place.)

When used with the 3070 high speed scanning module, the sample and hold circuits of the 3061 and 3063 can hold multiple input signals while the signals are multiplexed. Each 3061 (and 3063) can be triggered to hold the waveforms at the start of the scan. This means that when several analogue inputs are being sampled, the samples from all the inputs are held at the same moment in time, achieving simultaneous sampling.

Specifications as 3060 plus
Acquisition time (S/H) <10 usec
Aperture time (S/H)    125 nsec
Droop rate (S/H)       0.04 mV/msec

Microlink 3062 - Analogue Input with Anti-Alias Filter

The 3062 incorporates a high quality instrumentation amplifier preceded by an anti-aliasing filter to remove high frequency contamination. The filter is programmable in 256 steps around the nominal frequency. You can turn it off from software

Anti-Aliasing Filters
Anti-aliasing filters are commonly used to reduce errors in A-D converter based systems. They provide a high frequency cut-off for the signal which goes into the converter, thereby reducing the generation of false, low-frequency signals caused by too low a sampling rate. For a 12-bit A-D, attenuation of -78 dB will reduce out of band signals to less than the quantisation level of the A-D converter. The normal guidelines for selecting the cut-off frequency for the filter are as follows.

Signal TypeCut-Off Frequency Criterion
pulsed DCrate of change (V/sec)1V
sinusoid1/period
complex periodic20/fundamental
single events1/pulse width
Specifications as 3060 plus
Type of A-A filter   4 pole standard
                     8 pole available
Cut-off frequencies  Programmable in 256 steps around
                     nominal frequency
Nominal frequency    To order

Microlink 3063 - Analogue Input with Anti-Alias Filter and Sample/Hold

The 3063 module consists of a high quality instrumentation amplifier preceded by both a programmable anti-aliasing filter and a sample and hold circuit. It incorporates the features of both the 3061 and 3062 in one module.


Software Support

You can control the Microlink 3000 with Windmill, Streamer, SCAN1000 or Excel software. The serial Microlinks (those that communicate over RS232 or RS485) can be OPC-enabled. With the addition of their OPC-server software you can use them with any OPC client software such as Hexatec's Saturn SCADA software and National Instruments' LabVIEW. Another option is to program the Microlink yourself: ask for our programming manuals and example programs.


Use with the 3070 High Speed Scanning Module

The analogue input facilities of the Microlink can be used in 2 modes. Systems without a 3070 module, or with the 3070 disabled, take single samples on demand. The computer addresses one of the analogue input modules, which then connects its signal to the analogue-to-digital converter. A single conversion is performed and the digitised data passed to the computer. In this mode, sampling is controlled directly by software. Much faster speeds are available when a Microlink 3070 module is used. The channels to be digitised are then selected before data collection begins.


Other Analogue Input Options

The Microlink 3000 system is the leading, modular, data acquisition and control system. However, it may be that your needs can be met at a lower cost by a unit which plugs into your PC's USB port. If this is the case see our USB overview.


More Information

For more information about monitoring analogue signals, please send for our free Systems Catalogue. Alternatively ask our advice on your project.

For more details on monitoring analogue signals: