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Radio Microlog In Service Data Logger
Radio Microlog
User Guide
Document No.
JRD-110728- 01
Issue Number
Issue Date
Product Code(s) :
Radio Microlog v3.1
JR Dynamics Ltd
Unit 4, Arcot Court,
Nelson Industrial Estate
Cramlington, Northumberland
NE23 1BB, UK
· machine dynamics, noise and vibration, NVH
· failure analysis, fatigue and accelerated life testing
· specialised instrumentation, data acquisition and analysis
· rotating machinery design and troubleshooting:
gearboxes, shafts, bearings, couplings, belts and chains
T +44 (0) 191 58 000 58
F +44 (0) 191 58 000 59
E [email protected]
Company registered in England No. 3284935 VAT Registration No. GB 660 2407 64
Radio Microlog In Service Data Logger
Document History
JR Dynamics Ltd
28 July 2011
Changes / Comments
First issue for Radio Microlog v3.1
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Radio Microlog In Service Data Logger
Design of new mechanical systems, and problem solving of
existing ones, requires accurate information about static and
dynamic in-service loads. Transmission Dynamics has
instrumentation, allowing measurement of strain, temperature
and acceleration in demanding industrial applications.
Radio Microlog is a miniature 2-channel, 16-bit instrument measuring just 45x34x15 mm, and
designed for long term unattended data logging. Microlog is also a powerful dual channel telemetry
system used to wirelessly transfer data from rotating machinery. Although Radio Microlog is
predominantly designed to operate with strain gauges, it can be interfaced with most standard
sensors which produce an electronic output. Radio Microlog samples at rates of up to 4kHz per
channel, and can log and evaluate real time loads simultaneously on two channels. Rainflow cycle
counting is simultaneously conducted during data logging, and is widely used for statistical evaluation
of fatigue life based on long-term acquisition of the field data.
Radio Microlog is equipped with Bluetooth digital radio
communication for remote programming, interrogation and data
downloading, as illustrated in the schematic diagram. Special
versions for specific installations in shafts or couplings, etc. can be
supplied to suit the available space envelope or application.
An internal backup battery and real-time clock guarantee over 20
hours‟ full data retention in case of external power failure, whilst
the flash data memory allows permanent retention of time at level
and Rainflow count data in case of power supply failure. The
control software is activated from a PC, and uses Bluetooth wireless communication to connect with
the Radio Microlog. The external computer is only used to program Radio Microlog, and to download
data for reporting or further analysis. The range of wireless communication depends upon the
immediate surroundings, but is typically not less than 30 m, and can be up to 100 m with an optional
higher gain antenna.
Radio Microlog is typically powered from a 3.7 to 15 V DC power supply or batteries. Higher or lower
supply voltages can be accommodated by using a suitable voltage converter or voltage regulator. The
small size of the device allows it to be positioned in restricted locations, allowing unattended data
collection on rotating or reciprocating machinery. Unattended long term stress analysis can be carried
out without tying up expensive man-hours or scarce equipment.
A typical Radio Microlog installation is shown here,
magnetically mounted to a wind turbine input shaft and
logging strain in torsion and bending. The Radio Microlog is
installed in the housing which also carries the batteries.
In the example shown here, the customer is able to regularly
download data from ground level, so no technician has to
climb the wind turbine except to install and decommission
the equipment.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
2 - Typical steps for an installation using Radio Microlog
2.1 - Install the transducer
Typically this will be a strain gauge. Radio Microlog is supplied configured for a full bridge. If quarter
or half bridge configurations are used, then completion resistors can be installed. Contact
Transmission Dynamics if you require this option. Alternatively, a separate bridge completion circuit
external to the Radio Microlog, also available from Transmission Dynamics, can be used.
2.2 - Mount the Radio Microlog
Radio Microlog can be securely
mounted using the four M3x0.5
mounting screws supplied with
the unit. Suitable tapped holes
must be spaced as shown in
the diagram. The mounting
screw holes are accessible by
loosening the four M2x0.4
screws and removing the lid.
2.3 - Connect the transducer
Having removed the lid, strain gauge connection to the
Radio Microlog is via the screw terminals as indicated by
the annotation on the base (and lid).
2.4 - Connect the power to the Radio Microlog
DC power connection to the Radio Microlog is as
annotated on the base (and lid).
2.5 - Install the PC application software
If you already have a previous version of the Microlog client installed on your PC, you must first
remove it. Go to Control Panel, Programs and Features (Windows 7/Vista) or Control Panel, Add or
Remove Programs (Windows XP), right-click „Radio Microlog‟, and choose „Uninstall‟.
Insert the setup disc included within the Microlog package to your computer, and launch „setup.exe‟.
Follow through the on-screen instructions to set up the application. After setup has completed, you
can launch the application from the „JR Dynamics Ltd‟ folder in Start, All Programs.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
2.6 - Connect the USB Transceiver to the host PC
Using the USB (A to mini-B) cable supplied.
Windows will show an information bubble in the bottom-right of
the screen, “Installing Device Driver Software…” or “Found new
hardware”, and should locate the appropriate drivers
automatically. Windows Vista or XP may ask you to provide
drivers manually so the transceiver can be installed. These are
included on the CD in the „Drivers‟ folder.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
3 - Controlling Radio Microlog from the PC via the USB Transceiver
3.1 - Establish Bluetooth connection to Radio Microlog
When the Bluetooth Data Transceiver is connected to a USB port of the PC and the Radio Microlog
application is started, you will see the Communications Options screen. The Serial Communications
port is automatically detected (but this might require reassignment, depending upon the host PC).
Previously saved data can be viewed by selecting Off-line Mode, without any need to have the
Bluetooth Data Transceiver connected, or a wireless connection to Radio Microlog.
To establish the Bluetooth connection to Radio Microlog, ensure that it is powered and within range of
the transceiver, then click „Connect‟.
Correct power connection to Radio Microlog is indicated by the green flashing LED in the lid.
Immediately after being powered up, Radio Microlog is available for Bluetooth connection for a five
minute period. If no suitable connection is found, it then disables the Bluetooth module to conserve
power for a five minute period. It subsequently reactivates the Bluetooth module at five minute
intervals and checks for a connection, allowing 40 seconds to discover the Microlog. The five minute
off – 40 seconds on cycle continues.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
After clicking „Connect‟ you will see
the following screen, and as Radio
Microlog becomes available for
connection it will appear in the list
of Bluetooth devices.
When the required device appears,
click Select and the Bluetooth
connection will be established.
After two minutes of „Waiting for
devices…‟ the „Refresh‟ bar
becomes active, and must be
clicked to continue the search for
3.2 - Main Menu
From the Main Menu, options can be selected to:
Reconfigure Radio Microlog parameters (identity, gain, zero offset, units, calibration);
Control data logging;
Activate telemetry operation;
Download stored data from Radio Microlog to the host PC;
Save data to file.
These operations are described in more detail in the following pages.
Each time any activity is performed
with the connected Radio Microlog,
the connection duration of five
minutes is restored. A second by
second countdown is shown in the
lower left part of the Main Menu
screen. After five minutes (300
seconds) without activity, Radio
Microlog disables the connection
for 5 minutes to conserve battery
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Radio Microlog In Service Data Logger
3.3 - Hardware Settings
Certain settings can be adjusted to tailor Radio Microlog to a specific measurement task by clicking
the Hardware Settings button in the Main Menu.
3.3.1 – Changing Radio Microlog Identity
The Radio Microlog Name can be
changed; this can be useful where
more than one device is used on a site.
Note that after clicking Apply to
change the Radio Microlog name, the
Bluetooth connection is lost and should
be re-established as described in
section 3.1 to continue Hardware
Setting adjustments. Your Microlog will
now be listed under its new assigned
3.3.2 – Syncing Radio Microlog onboard Real-Time Clock (‘Reset time’)
The on-board real-time clock can be synchronised with the date/time of the host PC. The on board
time is used to time stamp each logged event. It should be noted that, when power is reconnected
after a power supply failure, Microlog automatically resumes its operation. In this case, time stamp
information will either be available from an onboard Real Time Clock (RTC) if the power supply failure
was shorter than 20 hours or, in case the RTC information was lost, reconstructed after the downlaod
of the data from the time set on the client PC. If there is no valid time information in the on-board
RTC, the time is automatically synchronised from the client PC when a Bluetooth connection is
established. This date/time can be manually adjusted from the Hardware Settings menu.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
3.3.3 – Adjust Software Gain
If, following initial measurements, the signal level is found to be lower than required; the gain can be
adjusted from the host PC via the USB transceiver. Set Gain is used to apply a scale factor of x1, x2
or x4 to the signal. It is a „software gain‟ and is always applied to both channels.
After any adjustment of the gain in
this way, the Channel Offset
(setting your zero level) should
be reset for both channels.
If even higher or lower gain is
required, this can be achieved by
changing the gain-setting resistors
within Radio Microlog.
soldering miniature surface mount
components should attempt this
operation. Alternatively, the unit
can be returned to Transmission
Dynamics and we will carry out the
resistor change. Hardware gains of
between 1 and 10,000 are possible (297 supplied as standard), and are channel independent.
3.3.4 - Adjust Channel Offset enables the zero level to be adjusted. This process effectively sets the
„no load‟ level for the Radio Microlog, from which significant events will trigger acquisition of the
signal(s) during data logging in Full Processing mode.
Following a scan of ADC values,
the Channel Offset is initially set to
mid-scale. This can be then
manually adjusted by changing
values in the DAC value box.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
3.3.5 - Hardware Gain Calibration
Selecting Hardware Gain Calibration shunts an internal precision 249 kΩ resistor across one arm of
the bridge (between +IN and GND terminals). The resulting value can be used to establish the
electrical gain of each channel, and also serves to verify the strain gauge and wiring integrity.
3.3.6 - Set Logger Units
The user can select which engineering units are used to display data. A known sensitivity value must
be entered on the Engineering Units screen. This sensitivity can be obtained from theoretical
calculations or, much better, from a full mechanical calibration.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
3.4 - Data Logging
By selecting Start Logging from the
Main Menu, data logging is
following options. Single or Dual
Channel mode is selected from a
drop-down menu at the bottom of
the screen, along with sampling
3.4.1 - Data Logging - Acquire Time Domain Data
A time history is logged to the
Radio Microlog memory, and is
then available to download to PC.
The start of logging can be
selected from the screen below.
The duration of logging is
determined from the number of
channels (1 or 2) and sampling
frequency (1 to 4,000 Hz), but once
started, will continue until the
Radio Microlog memory is full. In
this mode, the LED pulses red.
Sampling frequency
4,000 Hz
500 Hz
125 Hz
50 Hz
10 Hz
1 Hz
JR Dynamics Ltd
4 min 10 s
33 min 20 s
2 hr 13 min
5 hr 33 min
27 hr 46 min
277 hr
Acquisition duration in Time Domain mode
2 min 5 s
16 min 40 s
1 hr 6 min
2 hr 46 min
13 hr 53 min
138 hr
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Radio Microlog In Service Data Logger
Upon completion of the Time Domain
Data acquisition, the stored data can
then be downloaded from Radio
Microlog (select Download Data from
the Main Menu). The matrix illustrates
the progress of data transfer.
Download of the full memory takes
fewer than four minutes.
3.4.2 - Data Logging - Data Stream to PC
Gives a live streaming display on the
PC monitor of data at 800 Hz (single
channel) or 400 Hz (dual channel),
with the option to stream straight to
Operation in this mode also activates
the analogue outputs on the
Transceiver (0 to 3.3V), enabling
analogue data to be measured/
recorded on a third party data
acquisition system. This mode of
operation allows Microlog to function
as a powerful telemetry system.
Please note that in telemetry mode,
there is a constant 100 ms delay between the source and the signal replicated on the analogue
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Radio Microlog In Service Data Logger
3.4.3 - Data Logging - Full Processing Mode
This mode is suitable for unattended data logging, often for long periods (weeks or months). The user
commences logging and, upon seeing the Logging Started screen below, can disconnect from the
Radio Microlog and leave it in situ. Microlog will now proceed with an unattended mode of operation,
continuously logging and processing data.
Statistics of the input signals are
continuously logged as Time-AtLevel and Rainflow Count. The 100
highest events are stored as a time
history; the duration of each logged
time domain event depends on the
sampling frequency and number of
channels being logged.
100 highest events (each); Time domain event duration
Sampling frequency
4,000 Hz
500 Hz
250 Hz
125 Hz
50 Hz
1 Hz
1.125 s
9 s
18 s
36 s
1 min 30 s
1 hr 15 min
Acquisition duration
0.562 s
4.5 s
18 s
45 s
37 min 30 s
If a „high‟ event occurs once there are already 100 highest stored events, the lowest is discarded and
replaced with the new event.
The 100 highest events are held in volatile memory and are protected by a back-up battery if Radio
Microlog power is interrupted for up to 20 hours. This enables short power interruptions, to change
batteries for example, without loss of any stored data. Once power is restored within this timeframe,
Microlog will automatically resume logging with no user intervention required. The Time-at-Level and
Rainflow statistics of logged signals are stored in non-volatile memory and will be retained indefinitely,
even in the event of a long-term power interruption, until the user chooses to start capturing new data.
When required, the logged data can be downloaded, as previously described.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
During data download, logging is suspended. Once data transfer has completed, logging will resume
where it left off, with subsequent events being appended to the existing data. This will be useful for a
client wishing to download interim data without having to halt a test programme. In order to wipe the
Microlog and start capturing new data (including time-at-level and rainflow count statistics), a new
Logging session must be started (as outlined at the start of section 3.4.3).
When logging data in Full Processing Mode, the red LED blinks once per second; when an event
triggers data storage, the LED glows continuously for the duration of the event (which depends on the
sampling frequency selected at the start of data logging).
3.5 - Viewing Logged Data (Manage Datasets from Main Menu screen)
Manage Datasets is used to view
data downloaded from Radio
Microlog and then save it to PC, or
to Load previously saved data.
Details of hardware settings,
logging duration, and download
date and time are all recorded in
the Dataset Information.
Double click Rainflow Count, Time
At Level or 100 Largest Events
(Time Domain) to view the Logged
3.5.1 - Rainflow Count
Rainflow count data allows the
summation of fatigue cycles which,
in conjunction with an S-N curve,
can be used to estimate fatigue life
(ref. Miner‟s Rule summation).
The full input scale is divided into
32 bins for the mean and 64 bins
for the range, into which each
rainflow cycle is allocated.
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Radio Microlog In Service Data Logger
The logged data can be viewed as
a 2-D or 3-D graph, where the
„count‟ scale can be adjusted to
show more detailed data where the
count is low.
3.5.2 - Time At Level Data
Time At Level documents the
cumulative time histogram the
signal has spent at each value over
the entire logging period.
The full scale is divided into 64
ranges for this parameter.
3.5.3 - Largest Events
The 100 largest events are logged as time histories, the duration of which depends on the sampling
frequency and number of channels (see table on p.13). The events can be sorted by time/date or by
amplitude, and can be expanded to view detail of the signal.
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Radio Microlog In Service Data Logger
Individual events can be exported in tab delimited format (suitable for Excel).
The Overview
button allows the
100 largest event
time histories to be
quickly reviewed
on a single full
screen display.
Often, the most
important events
stand out at first
Clicking on the event of interest will close the Overview and display details of the selected event.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
4 - Radio Microlog Accessories and Options
Gain - Radio Microlog default hardware gain value is 297, but can be varied for each channel by
software or by changing the precision gain setting resistors.
Bridge Configuration - Radio Microlog default bridge configuration is for full bridge connection, but it
can be configured for half or quarter bridge connection on each channel by installing precision bridge
completion resistors within Microlog. Contact Transmission Dynamics if you require this option.
External Bridge Completion Board – Bridge completion boards (for half or quarter bridge gauges),
complete with a balancing potentiometer, are available. These miniature units offer easy external
conversion to full bridge configuration to be accepted by Microlog.
Remote data download via GSM network
Radio Microlog can be supplied with a dual mode long range transceiver, to enable communication
with the Microlog remotely via the GSM network and our secure server. The supplied client software
allows connections to remotely installed Micrologs via our server. All features (apart from live
telemetry streaming) are fully operational, allowing the operator to remotely configure hardware
settings, start logging and download recorded data from anywhere with internet access. Please note
this system requires an active SIM card (client‟s responsibility) for remote access via the GSM
The schematic diagram below shows a full Radio Microlog configuration, consisting of the Radio
Microlog, Battery supply, Strain Gauges and interconnecting wires. Additionally, there is a transceiver
containing a Bluetooth and GSM Module and Power supply unit.
3.7 – 15 V
Strain Gauges
To GSM Network
DC Power
AC Mains
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
Bespoke Radio Microlog and Battery Housings
The range of potential applications for Radio Microlog is very extensive, and the required operating
period varies for each client. Transmission Dynamics are able to design and manufacture bespoke
housings to enable the installation of Radio Microlog with the required battery life for a variety of
challenging applications. Examples are shown below.
Radio Microlog – Magnetically attached housing with batteries and
antenna, for wind turbine input shaft (20 rpm). This package forms
a complete stand-alone unit. Two pre-wired strain gauges are
bonded to the shaft with rapid setting two-part ceramic adhesive,
and connected via the screw terminals, allowing a complete
installation in just half an hour.
Radio Microlog „split disc‟ housing containing batteries,
installed on a 6 MW gas turbine generator coupling (1,500
Radio Microlog housed with a battery supply inside the gearbox
coupling of a rail locomotive (4,000 rpm). The system is set up as a
long range torque telemetry system, with the receiver mounted
inside the rail vehicle.
JR Dynamics Ltd
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Radio Microlog In Service Data Logger
5 - Radio Microlog v 3.1 - Specification Summary
Size: 45x34x15 mm
Weight: < 35 grams
Mechanical Protection:
Encapsulated to withstand 10,000 g shock
Bridge Excitation: 3.3 V fixed —other optional
Input protection: ±40V
Standard Gain: 297 (169 Ω gain-setting resistors)
1 to 10,000 set with other resistor values,
1x , 2x or 4x software gain selectable
Filter: Active 6-pole filter: -3 dB @ 4kHz
-120 dB roll off per decade
other optional
Bandwidth: Gain dependant,
typ. 2000 Hz -3 dB point @ G=1000
- Other available
CMRR: > 100 dB @ G=1000
Gain Tempco: < 50 ppm/ oC
A/D Converter: 2-channel, multiplexed,
16-bit resolution
Sampling rate: 4 kHz per channel
(single-channel mode)
Memory: 4 MB RAM; 256 kB non-volatile flash
Power Supply: 3.7 to 15V
- other (1V to 48V) available using external
voltage regulator or DC-DC converter.
50 mA @ 3.7 V incl. digital radio power
and 2 strain gauges
15 mA @ 3.7 V in radio stand-by mode
(between radio access time windows)
Inductive Power Supply recommended for longterm continuous monitoring of industrial
Reverse polarity: Fully protected
Operation temp.: -40 oC to +85 oC
JR Dynamics Ltd
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