Ele GDU 27-1500 User manual

GDU
27-1500
Original Instructions 1 9901X0265 Issue 2
OPERATING INSTRUCTIONS
US EDITION
GDU
27-1500
ELE International
Chartmoor Road, Chartwell Business Park
Leighton Buzzard, Bedfordshire, LU7 4WG
England
phone: [phone]
fax: [phone]
email: [e-mail]
http://www.ele.com
ELE International, a division of Hach Lange Ltd.
Distributor:
ELE International
Soiltest Product Division
PO Box 389, Loveland, CO 80539
USA
phone: [phone]
fax: [phone]
email: [e-mail]
http://www.eleusa.com
In the interests of improving and updating its equipment, ELE reserves the right to alter specifications to equipment at any time
ELE International 2015 

GDU
27-1500
Original Instructions 2 9901X0265 Issue 2
Contents
1INTRODUCTION AND SPECIFICATION 4
1.1 USE OF THIS MANUAL 4
1.2 GENERAL INFORMATION 4
1.2.1 Safety information 4
1.2.2 Precautionary labels 5
1.3 CERTIFICATION 6
1.4 ELECTRICAL SAFETY 6
1.5 THE GDU OPERATING SYSTEM 7
1.5.1 CPU Module 7
1.5.2 Analogue Input Module 7
1.5.3 Physical Specification 8
1.5.4 Replacement Parts 8
2INSTALLATION AND CONNECTION 9
2.1 INSPECTION 9
2.2 PRE-INSTALLATION CHECKS 9
2.3 INSTALLING ADDITIONAL INPUT MODULES 9
2.4 POWER CONNECTIONS 9
2.5 CONSTRUCTION 10
2.5.1 Dimensions 10
2.5.2 Mainframe Chassis 10
2.5.3 Internal Power Supply 10
2.5.4 Rear Panel 10
2.6 COMPUTER COMMUNICATIONS INTERFACES 11
2.7 CONFIGURING THE RS232 INTERFACE 11
2.7.1 Baud Rates and Word Formats 11
2.7.2 XON/XOFF protocol 11
2.7.3 RS232 Interface Connections 11
2.8 CONFIGURING THE ETHERNET INTERFACE 12
2.9 SWITCHING ON13
2.10 POWER FAILURE RECOVERY 13
3ANALOGUE INPUT MODULE WITH TRANSDUCER EXCITATION 14
3.1 GENERAL DESCRIPTION 14
3.2 SPECIFICATION 14

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27-1500
Original Instructions 3 9901X0265 Issue 2
3.3 INSTALLATION 15
3.4 SIGNAL INPUT CONFIGURATIONS 15
4CPU MODULE 16
4.1 GENERAL DESCRIPTION 16
4.2 SWITCH SETTINGS AND JUMPER 16
4.3 FIRMWARE UPDATES 16
5MAINTENANCE 17

GDU
27-1500
Original Instructions 4 9901X0265 Issue 2
1 INTRODUCTION AND SPECIFICATION
The GDU is a versatile instrument designed to accommodate the general logging
requirements of geotechnical engineers and scientists. Its intelligent interface allows
the user to work with a range of transducers that are common requirements for a range
of geotechnical tests. The GDU itself may be connected to any standard personal
computer via an RS232 interface.
1.1 Use of this Manual
This manual has not been written with the technical user in mind, that is, someone who
intends to write their own software to control the GDU and therefore needs to know
about the GDU Data acquisition Operating System command set (GDOS commands).
This user should refer to the GDU/GDOS Technical Manual 9901X0264.
1.2 General Information
In no event will the manufacturer be liable for direct, indirect, special, incidental, or
consequential damages resulting from any defect or omission in this manual. The
manufacturer reserves the right to make changes in this manual and the products it
describes at any time, without notice or obligation. Revised editions are available on
the manufacturer’s website.
1.2.1 Safety Information
NOTICE
The manufacturer is not responsible for any damages due to misapplication or misuse of
this product including, without limitation, direct, incidental and consequential damages, and
claims such damages to the full extent permitted under applicable law. The user is solely
responsible to identify critical application risks and install appropriate mechanisms to
protect processes during possible equipment malfunction.
AVIS
Le fabricant décline toute responsabilité quant aux dégâts liés à une application ou un usage
inappropriés de ce produit, y compris, sans toutefois s'y limiter, des dommages directs ou
indirects, ainsi que des dommages consécutifs, et rejette toute responsabilité quant à ces
dommages dans la mesure où la loi applicable le permet. L'utilisateur est seul responsable
de la vérification des risques d'application critiques et de la mise en place de mécanismes de
protection des processus en cas de défaillance de l'équipement.
Please read this entire manual before unpacking, setting up or operating this
equipment. Pay attention to all danger and caution statements. Failure to do so could
result in serious injury to the operator or damage to the equipment.
Make sure that the protection provided by this equipment is not impaired. Do not use
or install this equipment in any manner other than that specified in this manual.
S'il vous plaît lire l'intégralité de ce manuel avant de déballer, d'installer ou d'utiliser
cet équipement. Faites attention à tous les dangers et mises en garde. Ne pas le
faire pourrait entraîner des blessures graves de l'opérateur ou des dommages à
l'équipement.
Assurez-vous que la protection assurée par cet équipement ne soit pas compromise.
Ne pas utiliser ou installer cet équipement d'une manière autre que celle spécifiée
dans ce manuel.

GDU
27-1500
Original Instructions 5 9901X0265 Issue 2
DANGER
Indicates a potentially or imminently hazardous situation which, if not avoided, will result in
death or serious injury.
DANGER
Indique une situation de danger potentiel ou imminent qui, si elle n'est pas évitée,
entraînera la mort ou des blessures graves.
WARNING
Indicates a potentially or imminently hazardous situation which, if not avoided, could result
in death or serious injury.
AVERTISSEMENT
Indique une situation de danger potentiel ou imminent qui, si elle n'est pas évitée, pourrait
entraîner la mort ou des blessures graves.
CAUTION
Indicates a potentially hazardous situation that may result in minor or moderate injury.
ATTENTION
Indique une situation potentiellement dangereuse qui peut entraîner des blessures
mineures ou modérées.
NOTICE
Indicates a situation which, if not avoided, may damage the instrument. Information that
requires special emphasis.
AVIS
Indique une situation qui, si elle n'est pas évitée, peut endommager l'instrument.
L'information qui nécessite une attention particulière.
1.2.2 Precautionary Labels
Read all labels and tags attached to the instrument. Personal injury or damage to
the instrument could occur if not observed. A symbol on the instrument is
referenced in the manual with a precautionary statement.
This symbol, if noted on the instrument, references the instruction manual
for operation and/or safety information.
Electrical equipment marked with this symbol may not be disposed of in
European public disposal systems after 12 of August 2005. In conformity with
European local and national regulations (EU Directive 2012/19/EU). European
electrical equipment users must now return old or end-of-life equipment to the
Producer for disposal at no charge to the user.
Note: For return for recycling, please contact the equipment producer or
supplier for instructions on how to return end-of-life equipment, producer-
supplied electrical accessories, and all auxiliary items for proper disposal.
Ce symbole, s'il est apposé sur l'instrument, fait référence au manuel
d'instructions de fonctionnement et / ou de sécurité.

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27-1500
Original Instructions 6 9901X0265 Issue 2
1.3 Certification
Canadian Radio Interference-Causing Equipment Regulation, IECS-003, Class A
Supporting test records reside with the manufacturer.
This Class A digital apparatus meets all requirements of the Canadian Interference-
Causing Equipment Regulations.
Cet appareil numérique de classe A respecte toutes les exigences du Règlement sur le
matériel brouilleur du Canada.
FCC Part 15, Class ‘A’Limits
Supporting test records reside with the manufacturer. The device complies with Part 15
of the FCC Rules. Operation is subject to the following conditions.
1. The Equipment may not cause harmful interference.
2. The equipment must accept any interference received, including interference that
may cause undesired operation.
Changes or modifications to this equipment not expressly approved by the party
responsible for compliance could void the user's authority to operate the equipment.
This equipment has been tested and found to comply with the limits for a Class A
digital device, pursuant to Part 15 of the FCC rules.
These limits are designed to provide reasonable protection against harmful
interference when the equipment is operated in a commercial environment. This
equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential
area is likely to cause harmful interference, in which case the user will be required to
correct the interference at their expense. The following techniques can be used to
reduce interference problems:
1. Disconnect the equipment from its power source to verify that it is or is not the
source of the interference.
2. If the equipment is connected to the same outlet as the device experiencing
interference, connect the equipment to a different outlet.
3. Move the equipment away from the device receiving the interference.
4. Reposition the receiving antenna for the device receiving the interference.
5. Try combinations of the above.
1.4 Electrical Safety
Warning : With the exception of the slot in CPU and Analogue Input Modules,
the unit does not contain any user-serviceable parts.
Avertissement: À l'exception de la fente CPU et des modules d'entrées
analogiques, l'appareil ne contient aucune pièce réparable par l'utilisateur.
Do NOT attempt to open the case as dangerous voltages are present internally.
Ne pas essayer d'ouvrir le boîtier que les tensions dangereuses sont présentes
à l'intérieur.
Do NOT operate the unit if the supply cord appears damaged.
NE PAS utiliser l'équipement si le cordon d'alimentation semble être
endommagé.

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27-1500
Original Instructions 7 9901X0265 Issue 2
Only connect the equipment to a polarised earthed power socket.
Ne branchez l'équipement qu’à une prise de courant mise à la terre polarisée.
Switch off and unplug the equipment before cleaning.
Eteignez et débranchez l'équipement avant de le nettoyer.
1.5 The GDU Operating System
The GDU Data acquisition Operating System (GDOS) is the GDU control software that
runs in the GDU’s CPU. It is able to interpret the English-like commands (GDOS
commands) sent from a computer. These GDOS commands are used to configure the
GDU for data acquisition and control and additionally may be used to interrogate the
operating conditions of the GDU and recall logged data. Refer to the GDU Technical
Manual for details on the command syntax.
1.5.1 CPU Module
The GDU mainframe accepts one CPU module with its RS232 and Ethernet interfaces.
The module contains a microprocessor with the GDU operating system GDOS. The on-
board clock provides a 24 hour clock and calendar. It resides in the 5th slot to the far
right-hand side of the chassis. It should not be inserted in any other positions. The
Ethernet interface should only be connected to a host PC via an appropriate router.
1.5.2 Analogue Input Module
The GDU mainframe has four slots (slots 1 to 4) which can accept the analogue input
modules. The system can address up to 32 individual input channels where one
channel normally corresponds to one analogue input.
Each input module accepts up to eight analogue inputs. It also has a dedicated
analogue to digital converter (ADC) that converts the analogue input signal to digital
data. This data is transferred to the CPU for processing by the GDU system. Each
module also contains a precision instrumentation amplifier with 11 programmable gain
ranges (x1 to x1024).
After amplification any transducer signal offset can be optionally removed by the on-
board voltage generator, and the resulting signal digitised.
The GDU input module covers a wide range of transducer types. Full details are given
in sections 3 and 4. The following is a brief description of the facilities available.
The range provides for the connections of differential and single ended voltage
sources, with sensitivities ranging from +/-5V full scale to +/-10mV full scale. A 10V
supply is available for those sensors requiring excitation such as pressure transducers
and LVDT’s.

GDU
27-1500
Original Instructions 8 9901X0265 Issue 2
1.5.3 Physical Specification
Specifications
Details
Dimensions (W x D x H)
365 x 320 x 160mm (14.4" x 12.62 x 6.3")
Weight
6.4kg (14.3lb)
Enclosure
Aluminium die-cast, powder coated
Display
None
Protections Class
I, IP20
Pollution degree/installation
category
2; II
Power requirements
110-115/230VAC +10%, 50/60Hz, 115VA, single
phase
Operating Environment
Temperature: 0 to 40oC(32 to 104oF)
Humidity: 10 to 90%, non-condensing
Altitude: to 2000m (6590ft)
Storage Environment
Temperature: -40 to 70oC(-40 to 158oF)
Humidity: 10 to 90%, non-condensing
Memory
4Mb
Connections
RS232, Ethernet, DIN
Fuses
2.5A, T, 250VAC
1.5.4 Replacement Parts
WARNING
Personal injury hazard. Use of non-approved parts may cause personal injury,
damage to the instrument or equipment malfunction. The replacement parts in
this section are approved by the manufacturer.
AVERTISSEMENT
Risque de blessures corporelles. L'utilisation de pièces non approuvées
comporte un risque de blessure, d'endommagement de l'appareil ou de panne
d'équipement. Les pièces de rechange de cette section sont approuvées par le
fabricant.
The user replaceable parts include the AC inlet fuses, analogue input modules,
detachable power cord and CPU module.
See Maintenance section for details on fuse replacement.
Replacement/additional Analogue Input modules have the part number 1914B0046 or
27-1505.
Replacement CPU modules have the part number 1914B0065.
Replacement North American detachable power cord part number 8608-0012 (US
office) or 6099X0229 (UK office).

GDU
27-1500
Original Instructions 9 9901X0265 Issue 2
2 INSTALLATION AND CONNECTION
WARNING
Multiple hazards. Only qualified personnel must conduct the tasks described in
this section of the document.
AVERTISSEMENT
Dangers multiples. Seul le personnel qualifié doit effectuer les tâches détaillées
dans cette section du
document.
2.1 Inspection
Before shipping, the GDU was fully tested and any additional input modules that were
ordered with the unit will have been fitted. Carefully check that all modules are in place
and that there are no signs of damage.
2.2 Pre-Installation Checks
CAUTION
Before connecting power to the GDU, check that the voltage selection
switch is correctly set, the plug-in modules are correctly inserted and their
retaining screws are tightened.
Avant de brancher l'alimentation à la GDU, vérifiez que le sélecteur de
tension est correctement réglé, les plug-in modules sont correctement
insérés et leurs vis de fixation sont serrées.
2.3 Installing Additional Input Modules
The basic GDU consists of the chassis with a CPU with RS232 and Ethernet
interfaces.
For systems with one analogue input module, this is inserted in slot 1 as default.
Shock hazard, modules must not be plugged in or removed whilst the
system power is on.
Risque de choc électrique, les modules ne doit pas être branché ou
retiré, tandis que la puissance du système est en marche.
If additional modules are ordered with the GDU chassis, these will be fitted and tested
so that no installation will be necessary. When input modules are removed or supplied
separately, the installation details are given in the data sheet located in section 3.3.
2.4 Power Connections
The power connections for your GDU depend which model GDU you have.
If your GDU is designed to operate on 230V then you will have been supplied with a
fully moulded cable set fitted. A UK and EU approved cable set is provided. If the GDU
is designed to operate on 115V then a US style moulded cable set is supplied.
No other lead is supplied to connect the GDU to any of the alternative input power
supplies supported by GDU.

GDU
27-1500
Original Instructions 10 9901X0265 Issue 2
NOTICE
The GDU must be operated from a clean power supply or UPS (uninterrupted power
supply) or you may incur power down errors.
NOTICE
Position the equipment so it is not difficult to operate the disconnection device.
Placez l'équipement de sorte qu'il n'est pas difficile de faire fonctionner le dispositif
de déconnexion.
The GDU has two anti-surge (T) fuses that that are used to protect the unit in the
case of over-current conditions. There are two fuses. For fuse replacement,
reference the Maintenance and Specifications section and use only UL/CSA certified
parts in the positions shown below.
2.5 Construction
2.5.1 Dimensions
The GDU physical dimensions are as follows:
Height 3U (160mm)
Width 365 mm
Depth 320 mm
2.5.2 Mainframe Chassis
The mainframe chassis is of a modular construction that will enable you to upgrade
your GDU to satisfy further demands you may place on the unit. The backplane PCB
has 5 DIN 41612 type C sockets for easy module insertion.
There are 4 slots of which you may insert up to 4 analogue input module cards (slots 1
through to 4) dependent on the tasks you require the GDU to perform.
2.5.3 Internal Power Supply
The internal power supply provides all the necessary voltages to drive all the modules
that may be fitted.
2.5.4 Rear Panel
Situated on the rear panel you will find the power on switch/filter that provides AC input
for the unit. This is fitted with 2.5A anti-surge fuses.
The rear panel also has the output connectors to your computer, a 9 D-type connector
plug for RS232 communication and an RJ45 connector for Ethernet comms.
A USB connector which may be used for future firmware updates is also on the rear
panel.

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27-1500
Original Instructions 11 9901X0265 Issue 2
2.6 Computer Communications Interfaces
The GDU is currently pplied with an RS232 interface for communication with the host
computer. The interface connector is located on the rear panel of the GDU. The
connection is a 9 way D fixed plug for the RS232 interface. A separate Ethernet
connection is available which may be used as an alternative to the RS232 link.
Before connecting the GDU to the computer system it is recommended that the
following precautions be observed:
All peripheral devices should be turned off
Plug each peripheral and the host into the mains supply
All devices must have their grounds connected to the mains earth.
2.7 Configuring the RS232 Interface
The RS232 interface does not need configuring as it has a fixed baud rate/protocol.
The host computer must be able to support the following configuration.
2.7.1 Baud Rates and Word Formats
The rate at which devices can communicate is specified by a “Baud rate” or the number
of BITS/second. It is important that both transmitting and receiving devices operate at
the same rate. Data is transmitted as a burst of pulses comprising an initial START
BIT, followed by a number of BITS that constitutes a word.
Baud rate is 9600, Word size is 8 BITS with no PARITY check, and finally 1 STOP BIT.
2.7.2 XON/XOFF Protocol
This legacy mode where the host has no “listen” or input buffer for temporarily storing
data, eg. Apple or Hewlett Packard microcomputers, is not supported.
2.7.3 RS232 Interface Connections
The standard 9 way ‘D’ RS232 interface connector is located on the GDU rear panel
and has the following pin connections:
Pin
Signal
1
Protective Earth
2
TxD (from GDU)
3
RxD (to GDU)
4
Not connected
5
Signal 0v
6
Not connected
7
Not connected
8
Not connected
9
Not connected
Table 1 RS232 Interface Connections

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27-1500
Original Instructions 12 9901X0265 Issue 2
The GDU uses a form of software handshaking to control the data interchange
between it and the host computer and therefore does not use the interface handshake
lines. RTS and DTR are not driven by GDU. Before connecting to the host computer
consult the computer’s manual for details of its RS232 interface connections and what
handshake lines (if any) are used. Only three connections between the GDU and the
computer are necessary, TxD, RxD and Signal 0V. Take care to ensure that the data
transmitter at the computer end is connected to the data receiver at the GDU end and
vice versa.
2.8 Configuring the Ethernet Interface
The Ethernet interface may be used as an alternative to the RS232 link. Connection to
a host PC must be made via an appropriate router supporting 10BaseT.
The default device name of the GDU can be set via switch S1 on the CPU module
1914B0065. Switch S1-5 must be OFF. Depending on the nature of the network
system, it may take some time for the GDU’s register name to be recognised.
S1-1
S1-2
S1-3
S1-4
GDU Name
Off
Off
Off
Off
ELE-GDU00
On
Off
Off
Off
ELE-GDU01
Off
On
Off
Off
ELE-GDU02
On
On
Off
Off
ELE-GDU03
Off
Off
On
Off
ELE-GDU04
On
Off
On
Off
ELE-GDU05
Off
On
On
Off
ELE-GDU06
On
On
On
Off
ELE-GDU07
Off
Off
Off
On
ELE-GDU08
On
Off
Off
On
ELE-GDU09
Off
On
Off
On
ELE-GDU10
On
On
Off
On
ELE-GDU11
Off
Off
On
On
ELE-GDU12
On
Off
On
On
ELE-GDU13
Off
On
On
On
ELE-GDU14
On
On
On
On
ELE-GDU15
If the use of the registered name fails due to the network set-up then it may be
necessary to configure the IP address manually.
The GDU can be set to a static IP address by setting switch S1-5 to On. By
using the RS232 port a command is sent to configure the IP address. Refer to
section 2.7 on the RS232 comms protocol.

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Original Instructions 13 9901X0265 Issue 2
The command format is :-
IPCFG <IP address> <gateway address> <subnet mask>
For example IPCFG 192.168.1.10 192.168.1.254 255.255.255.0
If the IPCFG command is sent with no parameters, the unit responds with the
current IP configuration. This command may be used to confirm what IP
address has been assigned to the unit.
2.9 Switching On
The memory in the GDU is non-volatile and data is retained in the case of a power
outage. The system also has circuitry to detect a power failure.
On power up the system checks the power status and the integrity of any test data in
the memory. Both the blue POWER and red PWR FAIL indicators on the front panel of
the CPU module will be lit. If the memory check fails the red ERROR indicator will also
be on.
Unless there is a problem with the CPU the GDU should always power up on with the
PWR FAIL indicator on. Failure to do so may indicate that the data or firmware has
been corrupted.
2.10 Power Failure Recovery
The GDU’s data storage memory is retained in the absence of a mains supply. The
retention period for this memory is in excess of 5 years.
If the mains supply voltage drops below 200 VAC (or approximately 100 VAC in 110
VAC regions) the processor is liable to go into random states. However, special
memory protection is triggered if the supply drops below this level. If the supply
continues to fall the memory and RTC power are protected. When the mains power
returns to normal, the protection circuit waits momentarily for the power supplies to
stabilize and then allows the processor to start operating. If the memory fails on power
up the GDU indicates this with the ERROR LED.
Some test types may be able to continue in the event of a short power outage. The
PWR FAIL indicator is used as direct indication that a power-failure has occurred. This
is important if the GDU is to be left unattended for long periods of time, when this
indicator can act as “tell-tale”. On power up the GDU will be in the idle state and no
more tests can be started, data may only be retrieved if it is not corrupt. At the users
discretion some test types may continue although the test result cannot be guaranteed
to be accurate.
New tests should not be commenced until the PWR FAIL indicator has been cleared.
This is a protection feature as it forces the user to recall all previous readings into the
host microcomputer before continuing. After this, the GDU can be reset with the
RESET command to correctly initialise memory and all the GDU’s internal systems.
NOTE: if turning the GDU off and back on again does not cause the POWER Indicator
to come on then there may be a fault with the CPU, the internal or external power
supply or a blown fuse.

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Original Instructions 14 9901X0265 Issue 2
3 ANALOGUE INPUT MODULE WITH TRANSDUCER EXCITATION
3.1 General Description
The Analogue Input Module is a general purpose input scanner capable of accepting
up to 8 separate signal sources.
It has the part number 1914B0046 or 27-1505.
The input signals can range from +/-10 volts full scale when used with a system gain of
1, to +/-9.76 m.volts full scale when used with a system gain of 1024. The input
channels are connected to the system analogue to digital conversion module by an 8
channel 2 pole solid state multiplexer.
The module features a 10 volt stabilised power supply
for transducer excitation, thus simplifying the tasks of
connecting many types of sensor, and has input
overvoltage protection to prevent system damage in
the event of incorrect connections being made.
The module has built-in gain, offset circuitry and a 16
bit ADC. On the front of the module are 9 status
LEDs.
The top left LED indicates the module has been
correctly recognised by the CPU. The other vertical 8
LEDs down the centre of the module indicate the
channel selection status. These LEDs are on when a
particular channel has been ‘SET’.
The top LED is for channel 1, going down to the
channel 8 LED at the bottom.
3.2 Specification
Number of input channels 8 Differential
Signal Range +/-10 Volts Full Scale (x1 system gain) to
+/-9.76mV Full Scale (x1024 system gain)
Cross Talk Immunity @ DC 120 dB
Cross Talk Immunity @ 10 kHz 80 dB
Leakage Current 10 nA
Transducer Supply 10 Volts +/-10 mV
Stability 50 ppm/oC
Maximum current per module 500 mA
Maximum Input Voltage ± 14 Volts

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Original Instructions 15 9901X0265 Issue 2
3.3 Installation
Before installing the input module in the mainframe the 2 address switches (S1) on the
card must be set so that the module’s input channels correspond to those required. In
the following table the switches are numbered 1 and 2. The channels are set in blocks
of 8.
S1-1
S1-2
Ch. Range
DOWN
DOWN
1 to 8
UP
DOWN
9 to 16
DOWN
UP
17 to 24
UP
UP
25 to 32
Table 2 Module Address Selection
Having set the channel range, turn off the system power and insert the module into the
required I/O slot. The module can be plugged into any of the 4 I/O slots regardless of
the channel range selected but it is recommended that the left-most slot is used for
channels 1 to 8, the next slot for channels 9 to 16 and so on. Care must be taken not to
set up different modules with the same channel range.
3.4 Signal Input Configurations
Signals within the input module are switched to the input of a programmable gain
instrumentation amplifier. This amplifier will accept differential signals within a ± 14 volt
range of the system common (Signal 0V). For single ended inputs connect Signal 0V to
the –ve signal input. Ideally, this should be done at the signal source. If this is not
possible then make the link on the input module connector.
Table 3 5 Way Din Connectors and Screw Terminal Connections
Pin
Signal
1
-ve Channel Input
2
+ve Channel Input
3
Signal 0V
4
-5V Supply
5
+5V Supply

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Original Instructions 16 9901X0265 Issue 2
4 CPU MODULE
4.1 General Description
The GDU CPU consists of a microprocessor, non-volatile memory, Micro SD card and
various interfaces.
There are five status LEDs that indicate the current condition of
the CPU.
POWER : blue LED indicating that the 5V power is active.
SCAN : a green LED indicating the ADC cards are being
sampled.
ERROR : a red LED indicating error conditions, see below.
COMMS : green LED indicating comms traffic between the
GDU and host PC.
PWR FAIL : a red LED indicating a power fail has occurred
since the last system RESET.
Error LED
Flashes if there is no valid program in the SD card or program
space. Stays on for invalid data in the non-volatile memory. Is
on if there is an invalid comms message, then cleared when
the host PC sends an ERROR message.
4.2 Switch Settings and Jumper
There are two eight bank DIP switches (S1 and S2) on the
GDU CPU.
Switch S1 is used for test mode and Ethernet setup (where
applicable, see section 2.8).
Switch S2 is reserved for development use.
.
4.3 Firmware Updates
The CPU contains a flash memory device that holds the firmware for the GDU. This
device will appear as a memory device when connected to a PC via the USB
connection on the rear panel. The green COMMS LED on the CPU front panel should
be on continuously when this occurs. The firmware can then be updated by copying
(over-writing) the latest GDU_BOOT.BIN file to the memory device. Once this has been
done, do not eject the device, instead remove the USB cable. The SCAN, ERROR,
COMMS and PWR FAIL LEDs should then flash as the programming sequence
completes. If updating is successful the ERROR LED will be off.

GDU
27-1500
Original Instructions 17 9901X0265 Issue 2
5 MAINTENANCE
DANGER
Multiple hazards. Only qualified personnel must conduct the tasks described in this
section of the document.
DANGER
Dangers multiples. Seul le personnel qualifié doit effectuer les tâches détaillées
dans cette section du document.
NOTICE
Do not disassemble the instrument for maintenance. If the internal components must be
cleaned or repaired contact the manufacturer.
AVIS
Ne pas démonter l'appareil pour la maintenance. Si les composants internes doivent être
nettoyés ou réparés contacter le fabricant.
Clean the instrument
Clean the exterior of the instrument with a moist clothe and a mild soap solution.
Replace the instrument’s fuse
DANGER
Fire hazard. Use the same type and current rating to replace fuses.
DANGER
Risque d’incendie. Remplacez les fusibles par des fusibles de même type et de
même calibre.
Fuse failure is typically caused by an instrument problem. If the fuse continues to fail,
contact Customer Service.
Refer to Specifications for fuse requirements.
1. Set the power switch for the instrument to off.
2. Remove the power cord for the instrument from the electrical outlet.
3. Use a flat-blade screwdriver to open the fuse drawer.
4. Remove the fuse drawer and replace the fuse.
5. Install the fuse drawer.