Microlink 3000: Modular Measurement and Control

Microlink 380x - Module Enhancers

The Microlink 3000 system comprises a frame of modules each dedicated to a specific task: voltage input, counting, output control, etc. The 380x Series provide extra capabilities for some of the modules.

Module Summary

Module Width:2111111
Used with:30503020/130713050305030503050
Number of channels:4818121
Function:pH inputsOpto-isolated
up/down counting
analogue input
Count to Voltage
Frequency to Voltage

3800 - 4 pH Inputs

pH electrodes have a very high input impedance and so you cannot connect them directly to the Microlink 3050 analogue input module. Instead connect them to the BNC sockets on the Microlink 3800, which are input protected. The 4 amplifiers on the 3800 convert the pH signals to a level acceptable by the Microlink 3050 analogue input module, so you can simply connect the 3800 to the 3050 by a ribbon cable. You can thus take pH measurements alongside, for example, temperature measurements.

As pH readings change relatively slowly we recommend the 3044 or 3045 analogue-to-digital converters. These are integrating converters with sample rates of up to 12.5 or 40 samples per second.

As well as the 4 pH inputs the 3800 has screw terminals for the other channels of the 3050.

3801 - Opto-Isolation for the 3020/3021

The 3801 module uses opto-isolators to drive the 8 counters of the 3020 or 3021 modules. This means that the gate (or enable) inputs of the 302x need not be used. the opto-isolator inputs are on a row of 16 terminals. A selection of resistor values are available so the 3801 can cope with a variety of input voltages. The maximum count rate with the 3801 is 5 MHz. A ribbon cable connects the 3801 to the 3020 or 3021.

3802 - 16-Bit Up/Down Counter

The 3802 uses the 3071 buffer module to store its ocunt prior to transfer to the computer. This allows the count to be included in a high speed scan. Exactly when the ocunt is stored in the buffer can be determined either by the 3070 high speed scanning module or by an external signal.

The 3802 can be used in several wasy. It can be used simply as a totalise counter which is set to 0 at the start of a high speed collection and read once per scan. It can track a rotary encoder, reading it at high speed. It can ocunt the number of pulses occurring per unit time, as in atomic particle counting. this would involve latching and resetting the counter at each high speed scan. It can also measure the period of time between pulses using its 1 MHz clock input.

3803 - 8 Isolated Analogue Inputs

With the 3803 module the first 8 channels of the 3050 analogue input module can be isolated. The 3803 is connected to the 3050 by a ribbon cable. The isolation inputs consist of a row of 16 screw terminals. Each 2 wire input has an impedance of 120 kOhm and a gain of 1. The first stage gain can be altered to accommodate smaller or larger signals than 10 V, in fact signals of 100 V or more can be handled. When dealing with smaller signasl the 3803 gain should be changed rather than the 3050, as altering the 3050 gain would just amplify the noise.

3804 - Count to Voltage Conversion

The 3804 is an up/down counter which converts its count to a voltage output suitable for a 3050. It consists of a 12-bit counter plus a 12-bit digital-to-analogue converter. In addition it has a low pas filter to produce smoothed voltages from data which itself might be quite noisy. The maximum count rate is 10 MHZ.

As the 3050 which receives the cout could be included in a high speed scan, the 3804 has similar applications to a 3802.

3805 - Frequency to Voltage Conversion

The 3805 module is used, for example, if you want to transfer frequency data to Windmill Streamer - a high speed data collection program running under Microsoft Windows. The 3805 has an opt-isolator input for the frequency which allows different voltage levels to be handled. It has 2 channels that will be tailored to your required frequency range. All connections are via a single D type connector.

3806 - LVDT Excitation

The 3806 module incorporates an LVDT signal conditioner to provide excitation and conditioning required for an AC LVTD (linear variable displacement transducer).

Software Support

You can control the Microlink 3000 with Windmill, 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.

More Information

For more information about monitoring pH see our pH notes. We also have an article on trouble-shooting pH measurement systems. Other questions, just ask.


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