MicroLinks Tech 770 User manual

Microlink 770
Manual
Biodata Limited

Manual Code: 770PDF-1.1
Issue Date: November 2015
Information in this document is subject to change without notice.
Updates are listed on our web site at
http://www.microlink.co.uk/techsupp.html
Biodata Limited 2011http://www.windmill.co.uk/help/http://www.windmill.co.uk/help/http://www.windmill.co.uk/help/
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Table of Contents
1Introduction 1.1
2Installing the Microlink 770 USB Unit 2.1
2.1 Plugging the Microlink 770 into the Computer 2.1
2.2 The Microlink’s Lights 2.1
2.3 Analogue Input Connection Notes 2.2
2.4 Clock and Trigger Connection Notes 2.7
2.5 Specifications 2.9
2.6 The 59x Screw Terminal Units 2.10
3Installing Windmill Software 3.1
3.1 Introduction 3.1
3.2 Installing Windmill Software 3.2
3.3 Configuring Your System 3.3
4Using Windmill with Microlink 770 Hardware 4.1
4.1 Introduction 4.1
4.2 Using SetupIML 4.1
4.3 The Rest of the Windmill Software Suite 4.8
I
Table of Contents

II
Microlink 770 Manual

Introduction
Thank you for purchasing the Microlink 770 High Speed Capture
Package. This Manual tells you:
•About the Microlink 770 unit and how to connect your
signals (Chapter 2)
•How to install the Windmill software (Chapter 3)
•How to use Windmill with the 770 unit
(Chapter 4)
To use the 770 system you need a PC with a USB port. It should be
running Windows 98SE, Windows 2000 or later.
The Microlink 770 unit plugs into the USB (universal serial bus)
socket of your computer. It provides the PC with 16 analogue voltage
inputs, which you can sample up to 100 000 times a second. When
Microlink 59x signal conditioning units are added, you can also use the
770 to monitor thermocouples, current, strain gauge bridges and bal-
anced bridges such as pressure transducers. The 59x units also allow
you to make your connections to screw terminals, rather than to the
37-way D connector.
Here is a brief list of the features of a Microlink 770 system.
•Independent input ranges let you mix different types of
measurements—thermocouples and 4-20 mA process
signals for example–without losing resolution (set with the
SetupIML software module).
•Use the 770 to switch on other equipment simultaneously
with the start of data capture (Section 2.4.4).
•Save data both before and after an event occurs (pre- and
post-trigger data). Useful for seeing, for example, what
happened immediately before a fault. (Set with the
Streamer software module.)
1.1
Introduction

•A digital input into the 770 lets other equipment trigger
data capture (Section 2.4.2).
•Alternatively wait until 1 or 2 readings cross a threshold
before automatically starting to collect data. For example,
when the temperature goes above or below your set
points (set with Streamer).
•Exclude channels from a scan. This lets you use the 770
with different set-ups without having to rewire, and maxi-
mises the speed of data capture. (Set with SetupIML.)
•Set both the interval between reading each channel (ther-
mocouple, strain gauge, etc), and how often all channels
are read. For example, you may choose to wait a millisec-
ond between reading each channel, but after the last
channel has been read pause for 10 seconds before start-
ing again. (Available from both SetupIML and Streamer.)
•For more accurate timing than your computer clock allows,
you can connect an external crystal-controlled clock
(Section 2.4.3).
•All results presented in engineering units: oC, oF, etc (set
with SetupIML).
1.2Introduction
Microlink 770 Manual

Installing the
Microlink 770 USB Unit
This chapter tells you how to connect your signals to the Microlink
770,andaboutthe59xscrewterminalunits.Aftermakingyourconnec-
tions see Chapter 3for details of installing the Windmill software.
2.1 Plugging the Microlink 770 into the
Computer
Plugging the Microlink into your PC could not be easier: just use the
USB cable provided. You don’t have to switch off your computer
first—or even restart Windows.
The Microlink 770 is powered from the USB port. Unless you are
using strain gauges, you don’t need an extra power supply unit.
2.2 The Microlink’s Lights
The Microlink 770 has a green light labelled ENUM and a red light
labelled BUSY. Neither of these will come on until you have installed
the Windmill software.
ENUM ENUM stands for Enumerated. This is lit when the
Microlink has been powered on by the USB plug and
play controller. It is a good indication that the Windmill
USB driver software has been correctly loaded.
BUSY This is lit for the duration of each USB communication. It
is not active until the Microlink has been enumerated.
2.1
Installing the Microlink 770 USB Unit

2.3 Analogue Input Connection Notes
The Microlink 770 provides 16 differential analogue input channels
which you can use to measure voltages. With the addition of 59x units
you can also monitorthermocouples,current, strain gauge bridges and
balanced bridges like pressure transducers.
2.3.1 Differential Inputs
All the inputs are differential: for each input signal there are two sig-
nal wires. The measurement is the difference in voltage between the
two wires. The two signals go into separate high-impedance amplifiers
which monitor the voltage between the input and ground. The outputs
of the two amplifiersare then subtracted to give the difference between
the + and – inputs. For small signals differential inputs are much better
than single-ended inputs. This is because the subtraction of the volt-
ages on each of the input wires means that any voltage common to
both wires is removed, thus reducing noise.
It is important to remember that the voltages at both inputs must be
within the amplifier operating range. A classic error is to connect a bat-
tery between positive and negative inputs with no other connection.
Although the difference between the inputs is well defined, the actual
voltageateachinputcouldbeanything.Connecting one end of the bat-
tery to the 0 V input, either direct or via a resistor, would solve the
problem.
The 0 V of the Microlink 770 is connected to computer earth, which
is usually connected to the mains earth. When making your connec-
tions you should follow this policy.
a. If your signal source is “floating”, i.e. has no reference to mains
earth,then you mustprovide areference by connectingone end of
it to the 0 V input, either direct or via a resistor. The resistor could
have any value up to several MΩ. However large values could
cause 50 Hz problems if your signal source has much leakage to
earth.
2.2Installing the Microlink 770 USB Unit
Microlink 770 ManualAnalogue Input Connection Notes

b. If your signal source is itself earthed then you should connect only
positive and negative inputs. You should make no connection to
Microlink 770 earth.
2.3.2 Input Voltage Range
The Microlink 770 operates correctly with input voltages in the
range ±11 V. The inputs will reject voltages which are common to both
positive and negative inputs. These common mode voltages could be
as big as 10 V.
2.3.3 Maximum Input Voltage
The input multiplexers are protected to 20 volts beyond the power
supply. This means ±35 V if the Microlink is switched on, ±20 V if it is
switched off. When a voltage above the power supply is applied to the
unit, its protection mechanism comes into action and this draws some
current from the signal source. This effect can be a problem when the
computer is switched off as it now draws current from any signal. Extra
series resistors can be added to reduce this fault current. Such resis-
tors will also protect the unit from much higher voltages. However, they
Analogue Input Connection Notes2.3
Installing the Microlink 770 USB Unit
Figure 2.1 For floating signals you need to connect one end
of the signal to the 0 V input on pin 19

willresultinhighernoiseandslowersamplingrates. The extra resistors
can be conveniently housed on a 590 screw terminal unit.
2.3.4 Unconnected Inputs
You can leave unused inputs unconnected, but if you attempt to
read from these unconnected inputs do not expect to get 0 V. They
could be any value. If another connected channel has recently been
read, the unconnected input will return a similar value. This is not
crosstalk. It occurs because the input capacitance of the amplifier is
charged to the voltage of the previous channel and has little incentive
to change when connected to an open circuit.
2.3.5 High Impedance Signals
A similar effect to that described above can occur with high imped-
ance signal sources. When the source is selected it must supply
current to charge the amplifier input capacitance. A high impedance
signal source may take some time to do this so slowing the maximum
sampling rate.
2.3.6 Auxiliary Input
This input has all the facilities of the other sixteen. In Windmill soft-
ware it is reserved for measuring cold junction temperatures with
thermocouples or excitation voltage in bridge circuits. When you use a
593 thermocouple input unit or a 594 bridge input unit, the auxiliary
input is automatically connected as required by the software.
2.3.7 Use with Microlink 593 Thermocouple Input Unit
When used with this unit the auxiliary input is automatically con-
nected to the cold junction sensor. This is an RTD (resistance
temperature device) with 0.8 milliampere flowing through it. If inputs
are unconnected the thermocouple break detection circuitry will cause
them to read positive full scale.
Pins 18 and 37 (–15 V and +15 V) provide a power supply for the
593—don’t connect any other signals to these pins.
2.4Installing the Microlink 770 USB Unit
Microlink 770 ManualAnalogue Input Connection Notes

2.3.8 Use with Microlink 594 Bridge Input Unit
When used with this unit the auxiliary input automatically measures
the excitation voltage connected to the 594.
2.3.9 Analogue Input Pin Numbers
Make your connections to the analogue 37-way D connector as
detailed in the table.
Analogue Input Connection Notes2.5
Installing the Microlink 770 USB Unit

2.6Installing the Microlink 770 USB Unit
Microlink 770 ManualAnalogue Input Connection Notes
19 0 V
+15 V 37
18 –15 V
+ Auxiliary 36
17 – Auxiliary
+ Input 15 35
16 – Input 15
+ Input 14 34
15 – Input 14
+ Input 13 33
14 – Input 13
+ Input 12 30
13 – Input 12
+ Input 11 31
12 – Input 11
+ Input 10 30
11 – Input 10
+ Input 9 29
10 – Input 9
+ Input 8 28
9 – Input 8
+ Input 7 27
8 – Input 7
+ Input 6 26
7 – Input 6
+ Input 5 25
6 – Input 5
+ Input 4 24
5 – Input 4
+ Input 3 23
4 – Input 3
+ Input 2 22
3 – Input 2
+ Input 1 21
2 – Input 1
+ Input 0 20
1 – Input 0
Please read the Connection Notes on the previous pages before
making your connections.
Microlink 770 - 16 Analogue Inputs
Pin Connections for 37-Way D Plug (Wiring View)

2.4 Clock and Trigger Connection Notes
If you are using an external clock or trigger, make your connections
to the 15-way digital connector. (If you are using Streamer software for
triggering and timing you can ignore this section.)
2.4.1 Inputs
The+inputsaretiedto0V,andthe –inputsto5V, by10Kresistors.
This means that you may safely leave the inputs unconnected. Volt-
ages applied should be restricted to the range 0–5 V.
2.4.2 External Trigger Inputs
There are 2 trigger inputs to accommodate positive and negative
edge triggering.Forarisingedge to initiate sampling, connect your sig-
nal to Trigger +. For a falling edge to initiate sampling, connect your
signal to Trigger –. In both cases leave the unused input unconnected.
Your trigger pulse should be at least 1 µsec wide.
2.4.3 External Clock Inputs
Thereare2external clock inputs to accommodate positive and neg-
ative edge timing. To initiate a scan on a falling edge, connect your
signal to External Clock –. For a rising edge to start a scan, connect
your signal to External Clock +. Your clock pulse should be at least 1
µsec wide.
The active edge of the clock pulse causes each analogue channel
tobesampledinturnfromthe firsttothelast. Errors will resultifanother
clock pulse occurs before the previous scan is finished.
Use the Windmill SetupIML software to control the number of
channels included in the scan, and Windmill Streamer to set the inter-
val between sampling each channel.
Clock and Trigger Connection Notes2.7
Installing the Microlink 770 USB Unit

2.4.4 Trigger Output
This output goes to 5 V when the unit starts to sample. You can use
itas a trigger to synchroniseexternalequipment with the Microlink 770.
The output stays at 5 V until sampling stops.
2.4.5 Digital Pin Numbers
Make your connections to the digital 15-way D connector as
detailed below.
1RUN Output Signal
5 V when the 770 is sampling
Use to trigger external events
2External Trigger Input –
A falling edge on this input triggers the Microlink 770
3External Trigger Input +
A rising edge on this input triggers the Microlink 770
4External Clock –
A falling edge on this input causes one full scan to be taken
5External Clock +
A rising edge on this input causes one full scan to be take
80 V
All signals are 5 V logic levels. The + inputs are tied to 0 V by 10K
resistors. The – inputs are tied to 5 V by 10K resistors.
2.8Installing the Microlink 770 USB Unit
Microlink 770 ManualClock and Trigger Connection Notes

2.5 Specifications
2.5.1 Microlink 770 Unit
Dimensions (mm) 180 x 120 x 40
Maximum length of cable 5 m per cable
Maximum distance from PC can be increased by use of USB hubs
2.5.2 Analogue Inputs
Number of inputs 16
Maximum safe input voltage
Computer on ±35 V
Computer off ±20 V
Voltage Ranges ±10 V, ±1 V, ±0.1 V
Common mode range ±10 V
A-D Resolution 16 bits
Throughput 100 kHz
Maximum linearity error ±0.02%
Input impedance 100 MΩ
Crosstalk 75 dB
On resistance ~400 Ω
Switch off leakage <2 nA
Input bias current ±30 nA
Settling time to 0.01% 15 µsec
Initial accuracy of gain and offset ±1 LSB
Input noise voltage 2 µV rms
2.5.3 Trigger and Clock Inputs and Outputs
Signal compatibility 5 V logic level
Run output (external trigger) 5 V when sampling
Trigger input – Trigger on falling edge
Trigger input + Trigger on rising edge
External clock – Scan starts on falling edge
External clock + Scan starts on rising edge
+ Inputs Tied to 0 V by 10K resistors
– Inputs Tied to 5 V by 10 K resistors
Specifications2.9
Installing the Microlink 770 USB Unit

2.6 The 59x Screw Terminal Units
The Microlink 59x range provides screw terminals for the Microlink
770, allowingyou to permanently wire your signals.These 59x unitssit
next to the Microlink 770. Some of the 59x range allow transducers like
thermocouples and strain gauge bridges to be monitored by the 770.
Extra facilities are available when components are fitted, such as pro-
tection from high voltages. There are 3 units you can use with the
Microlink 770.
Microlink 590 Screw Terminals
Microlink 590-8a Screw Terminals with Current Measurement
Microlink 593 Screw Terminals with Temperature Measurement
Microlink 594 Screw Terminals with Strain Measurement
The 59x range is optional, so you can ignore the rest of this Manual if
you have bought just the Microlink 770 and Windmill package.
2.6.1 Microlink 590 Unit—Screw Terminals
The 590 is a boxed screw terminal card. Extra facilities available
with this card include:
•noise filtering,
•input protection from high voltages,
•higher voltage inputs than normal,
•contact closure inputs,
•ac inputs,
•current to voltage conversion,
•biasing to ground,
•external current source switching,
•programmable resistance.
CONNECTION
The 590 unit has space for 3 rows of 18 screw terminals. The row
nearest the front panel is connected to pin 19 of the analogue D con-
nector on the front of the Microlink. This pin is connected to 0 V. The
other 2 rows are connected to pins 1–18 and 20–37 as indicated by the
small figures by the terminals.
2.10Installing the Microlink 770 USB Unit
Microlink 770 ManualThe 59x Screw Terminal Units

FITTING APPLICATION COMPONENTS
Series Components
Component positions S1 to S37 (0.4 inch pitch) are available to
mount components in series with D-type pins 1 to 37. Only S1
and S37 are named on the PCB because of lack of space. How-
ever the numbering sequence is the same as that of the nearby
B1 to B37 components. To fit a component in series with, for
example, pin 10
•Place the component in the S10 position (level with B10),
•Solder it on the copper side,
•Cut the track under S10 at the point where it narrows.
The main application of series components is series protection
resistors.Thesecouldhave any value fromhundreds of ohms to
megohms depending on requirements.
Parallel Components
ComponentpositionsP0 to P17(0.2,0.3, 0.4 inchpitch)are pro-
vided to mount components across analogue inputs 0 to 15, 16
istheauxiliaryinput,17completesthepattern. Components can
be simply soldered into these positions.
Input Filters
Low pass analogue input filters can be produced by fitting resis-
tors in the 2 series elements of an analogue channel, and a
capacitor in the parallel element. For instance a filter can be
implemented on channel 1 by fitting resistors to S2 and S21 and
a capacitor to P1. Typical values would be 10 KΩand 1µF.
These would produce a cut off frequency of about 8 Hz.
2.6.2 Microlink 590-8a Unit—Screw Terminals with
Current Measurement
The 590-8A is a boxed milliamp currentdetection card, arranged as
8 current and 8 voltage inputs. The same extra facilities are available
with this card as with the 590.
The 59x Screw Terminal Units2.11
Installing the Microlink 770 USB Unit

2.6.3 Microlink 593 Unit—Screw Terminals with
Temperature Measurement
The Microlink 593 is an isothermal box specialised for monitoring
thermocouples. It includes a cold junction sensing RTD with an associ-
ated constant current source (0.8 milliamps). The RTD determines the
temperature at the termination point. This reference temperature is
used with the analogue input channel’s voltage reading to calculate the
temperature at the thermocouple junction.
The Windmill software automatically connects the cold junction to
the auxiliary channel and compensates for it. It reads the channel di-
rectly, showing the cold junction temperature in Celsius.
Protection from high voltage inputs is provided when series resis-
tors are added. Noise problems can be solved by fitting an input filter
and broken thermocouple leads can be detected.
The cold junction sensing circuitry is located between the two
leftmostrowsofscrewterminals.Thiscircuitryisconnected by the PCB
to the auxiliary channel. Bias resistorsarefitted to produce a small cur-
rent through the thermocouples. This allows thermocouple break
detection.
2.12Installing the Microlink 770 USB Unit
Microlink 770 ManualThe 59x Screw Terminal Units

2.6.4 Microlink 594 Unit—Screw Terminals with Strain
Measurement
The 594 is a boxed 16 bridge inputs card, which enables the 770
unit to monitor strain gauge bridges and balanced bridges such as
pressure transducers.
For strain gauges you need an external excitation voltage, which
can supply sufficient current to keep all the bridge circuits energised.
Four sets of 16 screw terminals give + and – excitation and + and – sig-
nalsforeachof16bridges.Two1kΩterminationresistors are mounted
in half bridge configuration whilst high quality 350 and 120 Ωresistors
can be provided for the completion of quarter bridges. The auxiliary
channel of the 770 unit monitors the excitation voltage.
When monitoring a bridge input, the Windmill software automati-
cally reads excitation voltage and performs the bridge calculation to
produce a reading in microstrain. You can set a zero reference level
and monitor changes relative to that level.
With the 594 unit you can configure each input channel for any of
the following inputs.
voltage input
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
gauges
The figure on page 15 shows the general arrangement of the
Microlink 594. For each input channel (0–15) there are 5 screw termi-
nals. These are arranged in 5 rows labelled, 0V, +EX , —EX, +IN, –IN,
withthechannelnumber printed by each terminal.Common to all chan-
nels are the POWER INPUT terminals and two precision resistors
connected across the power supply to form a half bridge. The power
The 59x Screw Terminal Units2.13
Installing the Microlink 770 USB Unit

input terminals are directly connected to the auxiliary channel of the
770. Windmill software reads this channel to measure the excitation
voltage for use in the bridge equations. Each channel has associated
with it 2 link mounting positions and one resistor position. These are:
Rx Position for mounting a quarter bridge completion resistor
Qx Link to short out the quarter bridge completion resistor
Hx Link to connect the half bridge to the –IN of channel x
2.14Installing the Microlink 770 USB Unit
Microlink 770 Manual
General Arrangement of Microlink 594