Geokon 8800-2-1A User manual

Instruction Manual
Model 8800 series
GeoNet Wireless
No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon, Inc.
The information contained herein is believed to be accurate and reliable. However, Geokon, Inc. assumes no responsibility
for errors, omissions or misinterpretation. The information herein is subject to change without notification.
Copyright © 2014-2018 by Geokon, Inc.
(Doc Rev N, 11/14/2018)


Warranty Statement
Geokon, Inc. warrants its products to be free of defects in materials and workmanship, under
normal use and service for a period of 13 months from date of purchase. If the unit should
malfunction, it must be returned to the factory for evaluation, freight prepaid. Upon examination
by Geokon, if the unit is found to be defective, it will be repaired or replaced at no charge.
However, the WARRANTY is VOID if the unit shows evidence of having been tampered with
or shows evidence of being damaged as a result of excessive corrosion or current, heat, moisture
or vibration, improper specification, misapplication, misuse or other operating conditions outside
of Geokon’s control. Components which wear or which are damaged by misuse are not
warranted. This includes fuses and batteries.
Geokon manufactures scientific instruments whose misuse is potentially dangerous. The
instruments are intended to be installed and used only by qualified personnel. There are no
warranties except as stated herein. There are no other warranties, expressed or implied, including
but not limited to the implied warranties of merchantability and of fitness for a particular
purpose. Geokon, Inc. is not responsible for any damages or losses caused to other equipment,
whether direct, indirect, incidental, special or consequential which the purchaser may experience
as a result of the installation or use of the product. The buyer’s sole remedy for any breach of this
agreement by Geokon, Inc. or any breach of any warranty by Geokon, Inc. shall not exceed the
purchase price paid by the purchaser to Geokon, Inc. for the unit or units, or equipment directly
affected by such breach. Under no circumstances will Geokon reimburse the claimant for loss
incurred in removing and/or reinstalling equipment.
Every precaution for accuracy has been taken in the preparation of manuals and/or software,
however, Geokon, Inc. neither assumes responsibility for any omissions or errors that may
appear nor assumes liability for any damages or losses that result from the use of the products in
accordance with the information contained in the manual or software.

TABLE of CONTENTS
1. INTRODUCTION .................................................................................................................................................. 1
1.1 SENSOR NODE..................................................................................................................................................... 1
1.2 NETWORK SUPERVISOR ...................................................................................................................................... 1
1.3 NETWORK CONSIDERATIONS .............................................................................................................................. 2
2. NETWORK INSTALLATION.............................................................................................................................. 4
2.1 ITEMS NEEDED.................................................................................................................................................... 4
2.2 CHANNEL CONFIGURATION ................................................................................................................................ 4
2.3 CONNECTING SENSORS ....................................................................................................................................... 5
2.3.1 Cable Gland Models (8800-1-1_) .............................................................................................................. 5
2.3.2 10-pin Bulkhead Models (8800-1-2_) ........................................................................................................ 5
2.4 ANTENNA INSTALLATION.................................................................................................................................... 5
2.5 BATTERY INSTALLATION .................................................................................................................................... 6
2.6 ACCESSORIES...................................................................................................................................................... 7
2.7 DEPLOYMENT MODE........................................................................................................................................... 7
2.8 STATUS BUTTON FUNCTIONALITY ...................................................................................................................... 8
2.8.1 Overview .................................................................................................................................................... 8
2.8.2 Supervisor .................................................................................................................................................. 8
2.8.3 Node ........................................................................................................................................................... 9
3. GEONET MULTIPLEXER..................................................................................................................................11
3.1 INSTALLATION ...................................................................................................................................................11
3.1.1 Mounting the Multiplexer..........................................................................................................................11
3.1.2 Lightning Protection .................................................................................................................................12
3.2 CONNECTING TO THE NODE ...............................................................................................................................12
3.3 CONNECTING SENSORS ......................................................................................................................................12
3.3.1 10-pin Bulkhead Models (8800-8-2) .........................................................................................................12
3.3.2 Cable Gland Models (8800-8-1 and 8800-8-3).........................................................................................12
3.3.3 Determining Correct Wiring .....................................................................................................................13
3.4 SHARED CHANNELS ...........................................................................................................................................14
4. GEONET ADDRESSABLE SENSOR NODES ..................................................................................................15
4.1 SENSOR WIRING.................................................................................................................................................15
4.2 TROUBLE SHOOTING ..........................................................................................................................................16
5. ADD ON MODULES FOR SUPERVISOR COMPATIBILITY WITH ETHER NET AND CELLULAR
MODEMS...................................................................................................................................................................17
5.1 INTRODUCTION ..................................................................................................................................................17
5.2 INSTALLATION ...................................................................................................................................................17
5.2.1 Setting up the 8800-2-4A (Cellular Modem Add-on) ................................................................................17
5.2.2 Setting up the 8800-2-4B (Ethernet Add-on).............................................................................................18
6. MAINTENANCE...................................................................................................................................................20
6.1 PREVENTING WATER FROM ENTERING THE ENCLOSURES..................................................................................20
6.2 BATTERY LIFE ...................................................................................................................................................20
6.3 REPLACING BATTERIES......................................................................................................................................21
7. TROUBLESHOOTING ........................................................................................................................................22
APPENDIX A. SPECIFICATIONS .........................................................................................................................23
A.1DEVICE SPECIFICATIONS ...................................................................................................................................23
A.2 RADIO SPECIFICATIONS.....................................................................................................................................23
A.2.1 Models Utilizing 2.4 GHz Radios .............................................................................................................23
A.2.2 Models Utilizing 900 MHz Radios............................................................................................................23
A.3 8800-8 MULTIPLEXER SPECIFICATIONS ............................................................................................................24

APPENDIX B. MODELS .........................................................................................................................................25
B.1 SUPERVISOR......................................................................................................................................................25
B.1.1 RS-232 (8800-2-1_ and 8800-4-1_)..........................................................................................................25
B.1.2 USB (8800-2-2_ and 8800-4-2_)..............................................................................................................25
B.2 NODE ................................................................................................................................................................25
B.2.1 Gland Seal (8800-1-1_ and 8800-3-1_)....................................................................................................25
B.2.2 Bulkhead (8800-1-2_ and 8800-3-2_) ......................................................................................................26
B.3 MULTIPLEXER ...................................................................................................................................................26
B.3.1 Gland Seal (8800-8-1 and 8800-8-3)........................................................................................................26
B.3.2 Bulkhead (8800-8-2).................................................................................................................................26
B.4 ADDRESSABLE SENSOR NODES .........................................................................................................................27
B.4.1 Gland Seal (8800-5-1_ and 8800-6-1_)....................................................................................................27
B.4.2 Bulkhead (8800-5-2_ and 8800-6-2_) ......................................................................................................27
APPENDIX C. CONNECTOR PINOUTS ..............................................................................................................28
C.1 TRANSDUCER CABLE CONNECTIONS.................................................................................................................28
C.1.1 Cable Gland, Models 8800-1-1_ and 8800-3-1_......................................................................................28
C.1.2 10-Pin Bulkhead, Models 8800-1-2_ and 8800-3-2_ ...............................................................................28
C.2 COMMUNICATION CONNECTIONS......................................................................................................................28
C.2.1 RS-232, Models 8800-2-1_ and 8800-4-1_ ..............................................................................................28
C.2.2 USB, Models 8800-2-2_ and 8800-4-2_...................................................................................................28
APPENDIX D. MODBUS .........................................................................................................................................29
D.1 PROTOCOL ........................................................................................................................................................29
D.2 SUPPORTED MODBUS COMMANDS....................................................................................................................29
D.3 CONNECTIONS SETTINGS ..................................................................................................................................29
D.4 SPECIAL CONSIDERATIONS FOR GEONET..........................................................................................................29
D.5 SYSTEM INFO TABLE ........................................................................................................................................29
D.6 NODE TABLES ...................................................................................................................................................30
D.7 EXTENDED MEMORY ........................................................................................................................................31
D.8 CONVERSIONS...................................................................................................................................................33
D.8.1 Battery Voltage ........................................................................................................................................33
D.8.2 Board Temperature ..................................................................................................................................33
D.8.3 Thermistor................................................................................................................................................33
D.9 DATA TYPES .....................................................................................................................................................34
APPENDIX E. SENSEMETRICS MANAGEMENT PLATFORM.....................................................................35
E.1 CHANNEL CONFIGURATION...............................................................................................................................35
E.2 STATUS BUTTON ...............................................................................................................................................36
APPENDIX F. FIRMWARE UPGRADE ...............................................................................................................37
F.1 PROCEDURE.......................................................................................................................................................37
F.2 TROUBLESHOOTING...........................................................................................................................................40

FIGURES
FIGURE 1-SINGLE CHANNEL NODE .............................................................................................................................. 1
FIGURE 2-NETWORK SUPERVISOR ............................................................................................................................... 1
FIGURE 3-CLUSTER TREE NETWORK TOPOLOGY ......................................................................................................... 2
FIGURE 4-WORKING AROUND OBSTRUCTIONS ............................................................................................................ 2
FIGURE 5-FRESNEL ZONE............................................................................................................................................. 3
FIGURE 6-CHANNEL SELECT SWITCH........................................................................................................................... 4
FIGURE 7-TERMINAL CONNECTIONS ............................................................................................................................ 5
FIGURE 8-BATTERY SELECT SWITCH ........................................................................................................................... 6
FIGURE 9-BATTERY DETAIL......................................................................................................................................... 6
FIGURE 10 -INSTALLATION ORDER ............................................................................................................................... 7
FIGURE 11 -BUTTON LOGIC (SUPERVISOR)................................................................................................................... 9
FIGURE 12 -BUTTON LOGIC (NODE) ............................................................................................................................10
FIGURE 13 -NODE WITH MULTIPLEXER........................................................................................................................11
FIGURE 14 -SAMPLE WIRING .......................................................................................................................................13
FIGURE 15 -DIP SWITCH SETTINGS .............................................................................................................................14
FIGURE 16 -6150E ADDRESSABLE MEMS AND ADDRESSABLE SENSOR NODE ...........................................................15
FIGURE 17 -ADDRESSABLE SENSOR NODE WITH 6150E INSTALLED ............................................................................16
FIGURE 18 –NPORT CONFIGURATION ..........................................................................................................................18
FIGURE 19 –UPDATE FIELDS........................................................................................................................................19
FIGURE 20 –ENTER IP ADDRESS FOLLOWED BY “:4001” .............................................................................................19
FIGURE 21 -EXTERNAL FLASH READ FLOW DIAGRAM ................................................................................................32
FIGURE 22 -EXAMPLE NETWORK CONFIGURATION .....................................................................................................35
FIGURE 23 -CHANNEL SETTING FOR SENSEMETRICS COMPATIBILITY MODE...............................................................35
FIGURE 24 -BATTERY SELECTOR SWITCH IN OFF POSITION ........................................................................................37
FIGURE 25 -J1 CONNECTOR DETAIL ............................................................................................................................37
FIGURE 26 -UPGRADE CABLE DETAIL .........................................................................................................................38
FIGURE 27 -CHANNEL SELECTOR SWITCH ...................................................................................................................38
FIGURE 28 -UPDATE PROGRESS ...................................................................................................................................39
TABLES
TABLE 1-CHANNEL SELECTION ................................................................................................................................... 4
TABLE 2-SENSOR WIRING ............................................................................................................................................ 5
TABLE 3-LED INDICATOR MEANING ........................................................................................................................... 8
TABLE 4-STANDARD SINGLE GAGE WIRING ...............................................................................................................13
TABLE 5-ADDRESSABLE SENSOR WIRING...................................................................................................................16
TABLE 6-BATTERY LIFE..............................................................................................................................................20
TABLE 7-DEVICE SPECIFICATIONS ..............................................................................................................................23
TABLE 8-2.4 GHZ MODELS.........................................................................................................................................23
TABLE 9-900 MHZ MODELS .......................................................................................................................................23
TABLE 10 -MULTIPLEXER SPECIFICATIONS .................................................................................................................24
TABLE 11 -RS-232 SUPERVISOR MODELS ...................................................................................................................25
TABLE 12 -USB SUPERVISOR MODELS........................................................................................................................25
TABLE 13 -GLAND SEAL NODE MODELS .....................................................................................................................26
TABLE 14 -10-PIN BULKHEAD NODE MODELS ............................................................................................................26
TABLE 15 -GLAND SEAL MULTIPLEXER MODELS........................................................................................................26
TABLE 16 -10-PIN BULKHEAD MULTIPLEXER MODELS ...............................................................................................26
TABLE 17 -GLAND SEAL ADDRESSABLE SENSOR NODE MODELS................................................................................27
TABLE 18 -5-PIN BULKHEAD ADDRESSABLE SENSOR NODE MODELS .........................................................................27
TABLE 19 -TRANSDUCER CABLE CONNECTIONS (GLAND SEAL) .................................................................................28
TABLE 20 -TRANSDUCER CABLE CONNECTIONS (10-PIN BULKHEAD).........................................................................28
TABLE 21 -COMMUNICATION CONNECTIONS (RS-232) ...............................................................................................28
TABLE 22 -COMMUNICATIONS CONNECTIONS (USB)..................................................................................................28
TABLE 23 -SYSTEM INFO AND SETTINGS .....................................................................................................................30
TABLE 24 -NODE TABLE DETAIL .................................................................................................................................30
TABLE 25 -CHANNEL DETAIL (SINGLE CHANNEL NODE) ............................................................................................31
TABLE 26 -DATA ARRAY DETAILS (EXT MEMORY) ...................................................................................................32

1
1. INTRODUCTION
GeoNet is a low power, wireless, data acquisition network, designed to efficiently collect data
from many points. GeoNet is especially beneficial in geographically challenging locations where
a wired infrastructure would be expensive, if not impossible. The system consists of a Network
Supervisor, Sensor Nodes, and Agent Software. (For information regarding the installation and
use of Agent Software, please see the appropriate product manual.)
Features:
•Worldwide operation at 2.4 GHz or select countries at 900 MHz
•Up to 100 Nodes per network (Fewer with the use of GeoNet multiplexers, see Section 3.)
•12 channels available
•Each Node is capable of storing more than one million data arrays
•Operates with alkaline or lithium batteries
1.1 Sensor Node
Sensor Nodes collect battery and temperature data and will read any of
Geokon’s vibrating wire sensors. Each Node can read one sensor by
itself, or up to eight sensors when connected to a GeoNet Multiplexer.
Nodes ship with the following accessories:
•One 2.1 dBi omnidirectional antenna (For other antenna possibilities,
please contact Geokon technical support.)
•Two D cell batteries
•Four desiccant packs
1.2 Network Supervisor
The Supervisor controls the network and is the aggregator of all data
collected by the sensor Nodes. While the Supervisor is similar to the
Nodes in that it will read battery and temperature data, it does not
accommodate a vibrating wire sensor. Data stored by the Supervisor
may be collected by using Agent software or any other Modbus
master. (For information regarding the use of Modbus with GeoNet
hardware please see Appendix D.)
Supervisors ship with the following accessories:
•Two D cell batteries
•Set of two screwdrivers, one Phillips Head and one Flat Head
•Four desiccant packs
•One firmware upgrade cable
•One RS-232 or USB communications cable (depending on the
model purchased)
•One 2.1 dBi omnidirectional antenna (For other antenna
possibilities, please contact Geokon technical support.)
Figure 1 - Single Channel Node
Figure 2 - Network Supervisor

2
1.3 Network Considerations
GeoNet uses network technology that is self-configuring and self-healing. Data from the Nodes
is either sent directly to the Supervisor, or it arrives via communication between the Nodes. This
effectively creates a cluster tree topology. Figure 3 illustrates this concept.
Figure 3 - Cluster Tree Network Topology
Each transmission from Node to Supervisor or Node to Node is considered one “hop”. Examples
of hops are shown in Figure 3 and Figure 4. Up to four hops can be made between a Node and
the Supervisor. With the ability to hop comes the ability for the Supervisor to communicate with
Nodes that have not established direct radio communication. Figure 4 shows how GeoNet
devices can operate around buildings or other barriers using hops.
Figure 4 - Working Around Obstructions

3
When using GeoNet it is important to take into consideration the radio environment, and to
understand the effect that obstructions have on radio signals. Obstructions between two antennas
can cause reflections of the transmitted signal. When these reflections arrive at the receiving
antenna, they may be in or out of phase with the signal that took a straight-line path. This
reflected signal may act as constructive or destructive interference with the received signal. For
optimum performance, Geokon recommends creating as much vertical space as possible between
the straight-line path and obstacles, including the ground. Figure 5 illustrates what is known as
the Fresnel zone.
Figure 5 - Fresnel Zone
If GeoNet is deployed to a site and communication cannot be established, it may be necessary to
elevate the devices, or to move them to a location where a radio link can be established. This
may require extending the readout cable of the attached sensors.

4
2. NETWORK INSTALLATION
2.1 Items Needed
To install a network, begin with the Supervisor and at least one Node that is within radio range
of the Supervisor.
2.2 Channel Configuration
Channels allow multiple networks to coexist in the same area. All devices are set to
communicate on channel one from the factory and do not need to be altered if operating a single
network in a given area. However, if multiple networks are within radio of one another then the
devices of each network must be set to different channels.
To set the channel on a Node or Supervisor:
1) Open the device by unscrewing the four captive screws on the front of the enclosure. Make
sure that no dirt, water or other contaminants are allowed to enter the enclosure.
2) Set the channel select dipswitch (shown in Figure 6) to any of the 12 valid positions listed in
Table 1.
3) Devices will only communicate with others that have been set to the same channel.
To prevent erratic behavior, there can be only one Supervisor on a particular channel. A
Supervisor with the same channel setting cannot be within radio range of any of the units of
another network.
Modbus
Address
and
Channel
1
2
3
4
1
OFF
OFF
OFF
OFF
2
ON
OFF
OFF
OFF
3
OFF
ON
OFF
OFF
4
ON
ON
OFF
OFF
5
OFF
OFF
ON
OFF
6
ON
OFF
ON
OFF
7
OFF
ON
ON
OFF
8
ON
ON
ON
OFF
9
OFF
OFF
OFF
ON
10
ON
OFF
OFF
ON
11
OFF
ON
OFF
ON
12
ON
ON
OFF
ON
13*
OFF
OFF
ON
ON
*
Sensemetrics Thread compatibility
mode, not for use with supervisor. See
Appendix E for more information.
Figure 6 - Channel Select Switch
Table 1 - Channel Selection

5
2.3 Connecting Sensors
A sensor may be attached to a Node before or after the Node has been powered on.
2.3.1 Cable Gland Models (8800-1-1_)
To wire a sensor on models featuring a cable gland:
1) Open the device by unscrewing the four captive screws on the front of the enclosure.
Make sure that no dirt, water or other contaminants are allowed to enter the
enclosure.
2) Loosen the nut on the cable fitting and remove the white plastic dowel.
3) Thread the transducer cable through the cable fitting.
4) Wire each conductor of the cable into the correct position in the terminal block by
pressing down on the corresponding orange tab at the back, inserting the conductor,
and then releasing the orange tab. (Refer to Figure 7 and Table 2 for sensor wiring
information.)
Position
Color
Description
VW+
RED
Vibrating Wire +
VW-
BLACK
Vibrating Wire -
TH+
WHITE
Thermistor +
TH-
GREEN
Thermistor -
SHLD BARE Analog Ground
(shields)
Table 2 - Sensor Wiring
5) Tighten the nut on the cable fitting so that it securely grips the cable. This must be
done to ensure that water does not enter the enclosure. (Beware of
overtightening, which may damage the plastic threads.)
2.3.2 10-pin Bulkhead Models (8800-1-2_)
Sensors are attached to the Node with a 10-pin Bulkhead connector. Align the grooves on
the sensor connector (male), with the connector on the unit (female). Push the connector
into place and then twist the outer ring of the male connector until it locks.
2.4 Antenna Installation
Remove the rubber cap from the antenna mount. Position the antenna on the mount and then
rotate the antenna in a clockwise direction until tightened.
Figure 7 - Terminal Connections

6
2.5 Battery Installation
Install the D cells in the Supervisor first, followed by the Nodes.
Install the batteries as follows:
1) Open the device by unscrewing the four captive screws on the front of the enclosure. Make
sure that no dirt, water or other contaminants are allowed to enter the enclosure.
2) Prior to installing the D cells, ensure that the battery select switch is set to the “OFF” position
(Figure 8). (For units manufactured prior to June 2017, move the battery select switch to the
OPPOSITE setting of the type of battery that will be installed.)
Figure 8 - Battery Select Switch
3) Install the batteries by aligning the positive (+) side of the D cells with the left side of the
battery holder. Push the batteries straight down into the holder.
Figure 9 - Battery Detail
4) Move the battery select switch to either the “Alkaline” or “Lithium” position depending on
the type of battery being used.
5) An LED will flash on the right side of the box indicating the unit has power.

7
2.6 Accessories
After the batteries have been installed:
1) Remove the desiccant packs from the plastic seal top bag they were shipped in and place
them inside the enclosure.
2) Reinstall the cover. Ensure that the rubber gasket clean and properly seated in the groove on
the underside of the cover. Tighten the screws a little at a time, working in a diagonal pattern.
Make sure the cover seals tightly and evenly.
3) Mount the device. The built-in mounting plate is designed to be used with U-Bolts, hose
clamps, screws, bolts, etc. Devices should be mounted with the antenna pointing up. (It is not
necessary to point the Node antennas in the direction of the supervisor, and vice versa.)
2.7 Deployment Mode
There are two modes of operation: deployment mode and normal mode. The Supervisor and
Nodes all enter deployment mode upon power up. Do not press the status button at this time.
(For information on the function of the status button, see Section 2.8)
With the Supervisor and Nodes both in deployment mode they will find each other in less than
three minutes (radio circumstances permitting). Once the network has been established, the
Supervisor’s red LED will flash simultaneously with the green LEDs on the Nodes. If the correct
lights do not illuminate, or if the unit has exited deployment mode because the status button has
been pressed, press the status button on the Supervisor again to restart deployment mode.
While in deployment mode, Nodes may be added by simply turning them on within radio range.
Any number of Nodes may be configured at one time; they do not need to be done
simultaneously. When adding Nodes, start with those closest to the Supervisor. It is desirable to
place the Supervisor in the center of the distribution of Nodes when possible (see Figure 10);
doing so will reduce hops, thereby reducing battery consumption.
Figure 10 - Installation Order

8
The default time a network will remain in deployment mode is one hour. When a new Node joins
the network the timer will reset, extending the deployment period for another hour. If more time
is needed while deploying Nodes, the default deployment timeout may be changed using Agent
software.
After 10 minutes, the LEDs on the Nodes will stop indicating their status in order to conserve
batteries. Pressing the status button on a Node will reactivate the LEDs for another 10 minutes.
Nodes may be moved to their install locations while the green LED is flashing. Observe the
LEDs while moving the Nodes to ensure a good communication path is maintained.
The network will not begin collecting data until the network time has been set. This may be
accomplished by using the Agent software (or other Modbus master). The default scan interval
for data collection is 10 minutes.
If isolated from the rest of the network, a Node will continue to sample and store data. When
communication is reestablished, it will “catch up” by sending all of the collected data to the
Supervisor.
2.8 Status Button Functionality
2.8.1 Overview
All GeoNet devices have red and green LED indicators to display their status. There is a
reference key printed on the side of each unit, below the LEDs. When the status button is
pressed, the appropriate LED indicators will briefly illuminate. Table 3 shows the
meaning of the various LED indications. (When used in a Sensemetrics network, see
Appendix E for the meaning of the LED indications.)
LEDs
Supervisor
Nodes
Time set, Nodes present
Radio signal > 30%
No Nodes present Radio signal < 30%
Network time not set No radio signal
Table 3 - LED Indicator Meaning
2.8.2 Supervisor
If the green LED on the Supervisor flashes when the status button is pressed, this
indicates that the network is entering deployment mode. In order to provide timely
feedback to the user, the network parameters will be changed to a 10-second radio
interval.
If the red LED flashes when the status button is pressed, the Supervisor is exiting
deployment mode and will resume normal operation.

9
Changes initiated by the status button will be made on the following radio cycle. This
could take up to three minutes when switching from normal mode to deployment mode,
as changes to the radio settings can only occur when all the radios in the network are
awake.
If the user presses the status button multiple times, the mode of operation will be
whatever is indicated by the final LED flash.
Figure 11 - Button Logic (Supervisor)
2.8.3 Node
If the green LED flashes on a Node when the status button is pressed, it will begin
indicating the status of the radio signal by flashing the LEDs during radio activity. If the
Node has not yet joined the network, it will also change its radio interval to
approximately one second.
If the red LED flashes when the status button is pressed, radio status indicating has been
disabled; no lights will flash thereafter.

10
Figure 12 - Button Logic (Node)

11
3. GEONET MULTIPLEXER
The GeoNet Multiplexer expands the number of vibrating wire sensors a Node can read from one
to eight. Channel switching is controlled by the Node and is accomplished by solid-state
(nonmechanical) circuitry.
Each Node with a Multiplexer attached uses the equivalent data of four single nodes. Since the
maximum number of Nodes per Network is 100, the maximum amount of Nodes with a
Multiplexer attached that may be connected to a single network is 25.
The Multiplexer is protected from environmental contaminants by a rugged, NEMA 4X
enclosure, constructed from fiberglass reinforced polyester. It is also shielded from harmful radio
frequencies and electromagnetic interference by a conductive gasket and internal RFI/EMI
coating. An Earth Ground terminal is provided on the exterior of the enclosure to protect against
lightning and other large, transient voltages.
Multiplexers ship with the following accessories:
•Four desiccant packs
•Two lithium D cells (These D cells must be installed in the Node to which the Multiplexer
will be attached.)
Figure 13 - Node with Multiplexer
3.1 Installation
3.1.1 Mounting the Multiplexer
The Multiplexer is typically mounted in such a manner that the cable entries are facing
downward (as shown in Figure 13 above). Attach the Multiplexer to the mounting surface
by utilizing the Multiplexer’s mounting plate. The mounting plate is designed to be used
with hardware such as U-Bolts, hose clamps, bolts, screws, etc. (Mounting hardware is
not included.)

12
3.1.2 Lightning Protection
Each VW (Vibrating Wire) channel is protected by a 230V gas discharge tube, followed
by a high-speed protector and a transient voltage suppression diode. Each TH
(Thermistor) channel is protected by a 230V gas discharge tube, followed by an inductor
(lower resistance than high-speed protectors) and a transient voltage suppression diode.
(See Section A.3 for complete specifications).
In order for these components to divert energy from a lightning strike safely to ground, a
solid electrical connection to earth ground needs to be made. A copper grounding rod, (at
least six feet in length,) should be driven into the soil to a minimum depth of three feet, as
close to the Multiplexer as possible. Alternatively, any other suitable attachment to earth
ground may be utilized. Connect the grounding rod to the copper grounding lug on the
exterior of the Multiplexer with a large gauge wire (12 AWG or larger). This will provide
a suitable path from the Multiplexer to ground in the event of a lightning strike.
3.2 Connecting to the Node
A Multiplexer can be added to a Node at any time; it will be detected and utilized automatically.
Install the lithium D cells into the Node that the Multiplexer will be connected to by following
the instructions in Section 2.5. Connect the Node to the Multiplexer by using a model 8032-5,
10-pin to 10-pin patch cord (sold separately). Align the grooves of the connector on the cable
(male), with the connector on the unit (female). Push the connector into place until seated and
then twist the outer ring of the male connector until it locks into place.
3.3 Connecting Sensors
3.3.1 10-pin Bulkhead Models (8800-8-2)
Sensors are attached to the Multiplexer with 10-pin Bulkhead connectors. Align the
grooves on the sensor connector (male), with the connector on the unit (female). Push the
connector into place and then twist the outer ring of the male connector until it locks.
3.3.2 Cable Gland Models (8800-8-1 and 8800-8-3)
1) Open the Multiplexer by loosening the four captive screws on the front of the
enclosure and removing the lid. Make sure that no dirt, water, or other
contaminants are allowed to enter the enclosure.
2) Loosen cable gland nuts and remove the white plastic dowels. To prevent
contaminants from entering the enclosure, dowels should be left inside cable fittings
that will not be used.
3) Thread the transducer cables through the cable fittings. (For simplest cable
management inside the enclosure, transducer cables should be wired sequentially,
from left to right, top to bottom.)

13
4) Insert the conductors of each cable into the terminal blocks of the multiplexer by
pressing down on the orange tab at the back of the terminal block, inserting the
conductor, and then releasing the orange tab. See Section 3.3.3 for information on
determining the correct wiring.
5) Tighten the nuts on the cable fittings. This must be done to ensure that water does
not enter the enclosure. Avoid overtightening as this may damage the plastic
threads.
6) Reinstall the cover. Ensure that the rubber gasket is properly seated in the groove on
the underside of the cover. Tighten the screws a little at a time, working in a diagonal
pattern; this ensures that the cover seals correctly.
3.3.3 Determining Correct Wiring
Geokon instruments with a single vibrating wire gage should be wired according to Table
4. (As shown on channels six, seven, and eight in Figure 14.)
Position
Color
Description
VW+
RED
Vibrating Wire +
VW-
BLACK
Vibrating Wire -
TH+
WHITE
Thermistor +
TH-
GREEN
Thermistor -
SHLD
BARE
Analog Ground (shields)
Table 4 - Standard Single Gage Wiring
To determine the correct wiring for Geokon instruments with multiple vibrating wire
gages, refer to the wiring chart(s) in the manual provided with the instrument. These
types of instruments will require the use of more than one channel in the Multiplexer. For
example, a five transducer Borehole Extensometer has been wired into channels one, two,
three, four, and five in Figure 14. For instruments that have multiple gages sharing a
single conductor, refer to Section 3.4, “Shared Channels”.
Figure 14 - Sample Wiring

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3.4 Shared Channels
Some Geokon instruments utilize multiple gages that share a single conductor for negative
polarity. During normal operation, each channel of the Multiplexer consists of four signals,
which are all switched together: VW+, VW-, TH+, and TH-. However, the Multiplexer can be
configured to switch the VW- signal separately from the rest, allowing for configurations where
multiple gages share one common VW- signal. This shared conductor may be connected to the
VW- on any of the channels to which the various gages have been wired.
Switching of the VW- signal is controlled by an eight-position DIP switch located on the left side
the circuit board. This DIP switch tells the Multiplexer which channels are sharing a common
VW- signal. Use the table located on the top left corner of the circuit board (reproduced in Figure
15) to determine which of the eight switches to move to the on position based upon which
channels are sharing a common VW- signal.
For example: If the VW+ conductors of a four gage load cell were wired into channels four, five,
six, and seven, then the common conductor for these gages may be wired into the VW- of any of
those four channels. Consequently, switches four, five, and six on the eight-position DIP switch
would be moved to the ON position.
Figure 15 - DIP Switch Settings
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