ELPRO ERRTS ALERT2 Instruction sheet

Revision 0.5
ERT-A2 Configuration Manual

ERT-A2 ALERT2 Configuration Manual
Revision 1.0
ii
General Notices
ELPRO products are designed to be used in industrial environments by experienced industrial engineering
personnel with adequate knowledge of safety design considerations.
ELPRO products use communications channels that are subject to noise and interference. The products are
designed to operate in the presence of noise and interference, but in an extreme case noise and interference
can cause product operation delays or operation failure. Like all industrial electronic products, ELPRO products
can fail in a variety of modes due to misuse, age, or malfunction. We recommend that users and designers
design systems using design techniques intended to prevent personal injury or damage during product
operation and provide failure tolerant systems to prevent personal injury or damage in the event of product
failure. Designers must warn users of the equipment or systems if adequate protection against failure has not
been included in the system design. Designers must include this Important Notice in operating procedures and
system manuals.
These products should not be used in non-industrial applications, or life-support systems, without first
consulting ELPRO.
The ERT-A2 modules operate standards based protocols to communicate. If your system is not adequately
secured, third parties may be able to gain access to your data via the radio link. Before deploying a system,
make sure that you have carefully considered the security aspects of your installation.
Follow instructions
Read this entire manual and all other publications pertaining to the work to be performed before installing,
operating, or servicing this equipment. Practice all plant and safety instructions and precautions. Failure to
follow the instructions can cause personal injury and/or property damage.
Proper use
Any unauthorized modifications to or use of this equipment outside its specified mechanical, electrical, or
other operating limits may cause personal injury and/or property damage, including damage to the
equipment. Any such unauthorized modifications: (1) constitute “misuse” and/or “negligence” within the
meaning of the product warranty, thereby excluding warranty coverage for any resulting damage; and (2)
invalidate product certifications or listings.
Product disposal
When your product reaches the end of its useful life, it is important to take care in the disposal of the product
to minimize the impact on the environment.
General instructions
The product housing is made of die-cast aluminium and may be recycled through regular metal
reclamation operators in your area.
The product circuit board should be disposed according to your country’s regulations for
disposing electronics equipment.
Europe
In Europe, you can return the product to the place of purchase to have the product disposed in
accordance with EU WEEE legislation.
Deployment of ELPRO products in customer environment
There is increasing concern regarding cybersecurity across industries, where companies are steadily integrating
field devices into enterprise-wide information systems. This is why ELPRO has incorporated secure
development life cycle in their product development to ensure that cybersecurity is addressed at all levels of
development and commissioning of our products.

ERT-A2 ALERT2 Configuration Manual
Revision 1.0
iii
There is no protection method that is completely secure. Industrial Control Systems continue to be the target
for attacks. The complexities of these attacks make it very difficult to have a complete secure system. A
defence mechanism that is effective today may not be effective tomorrow as the ways and means of cyber-
attacks constantly change. Therefore, it’s critical that our customers remain aware of changes in cybersecurity
and continue to work to prevent any potential vulnerability of their products and systems in their
environment.
At ELPRO we are focusing on helping our customers deploy and maintain our solutions in a secure
environment. We continue to evaluate cybersecurity updates that we become aware of and provide the
necessary communication on our website as soon as possible.
Product Notices
󱛺ATTENTION
INCORRECT TERMINATION OF SUPPLY WIRES MAY CAUSE INTERNAL DAMAGE AND WILL VOID
THE WARRANTY. TO ENSURE THAT YOUR 415U-2 WIRELESS I/O AND GATEWAY ENJOYS A LONG
LIFE, CHECK THIS USER MANUAL TO VERIFY THAT ALL CONNECTIONS ARE TERMINATED
CORRECTLY BEFORE TURNING ON POWER FOR THE FIRST TIME.
Safety notices
Exposure to RF energy is an important safety consideration. The FCC has adopted a safety standard for human
exposure to radio frequency electromagnetic energy emitted by FCC regulated equipment as a result of its
actions in Docket 93-62 and OET Bulletin 65 Edition 97-01.
󱛺CAUTION
TO COMPLY WITH FCC RF EXPOSURE REQUIREMENTS IN SECTION 1.1310 OF THE FCC RULES,
ANTENNAS USED WITH THIS DEVICE MUST BE INSTALLED TO PROVIDE A SEPARATION DISTANCE
OF AT LEAST 20 CM FROM ALL PERSONS TO SATISFY RF EXPOSURE COMPLIANCE.
DO NOT OPERATE THE TRANSMITTER WHEN ANYONE IS WITHIN 20 CM OF THE ANTENNA.
ENSURE THAT THE ANTENNA IS CORRECTLY INSTALLED IN ORDER TO SATISFY THIS SAFETY
REQUIREMENT.
Avoid
•Operating the transmitter unless all RF connectors are secure and any open connectors are properly
terminated
•Operating the equipment near electrical blasting caps or in an explosive atmosphere
󱛻󱛼󱛽Note: All equipment must be properly grounded for safe operations. All equipment should be serviced
only by a qualified technician.
FCC notice
Part 15.21—The grantee is not responsible for any changes or modifications not expressly approved by the
party responsible for compliance. Such modifications could void the user’s authority to operate the
equipment.
Part 15.105(b)—This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses and can radiate radio
frequency energy and, if not installed and used in accordance with the instructions, may cause harmful
interference to radio communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or television reception,

ERT-A2 ALERT2 Configuration Manual
Revision 1.0
iv
which can be determined by turning the equipment off and on, the user is encouraged to try to correct the
interference by one or more of the following measures:
•Reorient or relocate the receiving antenna
•Increase the separation between the equipment and receiver
•Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected
•Consult the dealer or an experienced radio/TV technician for help
Part 90—This device has been type accepted for operation by the FCC in accordance with Part 90 of the FCC
rules (47CFR Part 90). See the label on the unit for the specific FCC ID and any other certification designations.
󱛻󱛼󱛽Note: This device should only be connected to PCs that are covered by either a FCC DoC or are FCC
certified.
Manufacturer
Band
Model number
Description
Coax kit
Net
Gain
ELPRO
148-
174MHz
ANTB000300
VHF Dipole Whip 3dB Antenna c/w
5M Coax N type Connector
N/A
0 dB
ELPRO
148-
174MHz
ANTUDP150-C
48-174Mhz Aerial Dipole with N Type
Female
CCTAIL-SMA-M
2 dB
ELPRO
148-
174MHz
ANTB000100
VHF 3 dBd collinear 5dBi N Type
Female connector
CCTAIL-SMA-M
5 dB
ELPRO
148-
174MHz
ANTB000100
VHF 3 dBd collinear 5dBi N Type
Female connector
CC5-RG213
4.8 dB
ELPRO
340-
540MHz
ANTUDP400-C
Dipole Antenna 2dB gain with
100mm RG58 cable and 'N' Type
Female connector
CCTAIL-SMA-M
1.8dB
ELPRO
340-
540MHz
ANTUDP400-C
Dipole Antenna 2dB gain with
100mm RG58 cable and 'N' Type
Female connector
CC3-N
1.1dB
ELPRO
340-
540MHz
ANTBU3-400
Antenna 3dB Collinear with 'N' Type
Female Connector
CC10-N
1.9 dB
ELPRO
340-
540MHz
ANTBU6-400
Antenna 6dB Collinear with 'N' Type
Female Connector
CC10-N
4.9 dB
ELPRO
340-
540MHz
ANTYU3-400
400Mhz Aerial 3 element 6dBi YAGI
with 'N' Type Female connector
CC10-N
2.7 dB
ELPRO
340-
540MHz
ANTYU6-400
400Mhz Aerial 6 element 9dBi YAGI
with 'N' Type Female connector
CC10-N
5.7 dB
ELPRO
340-
540MHz
YU16/400
400Mhz Aerial 16 element YAGI
15dBi with 'N' Type Female
connector
CC20-N
8.4 dB

ERT-A2 ALERT2 Configuration Manual
Revision 1.0
v
Contents
General Notices................................................................................................................................... ii
Follow instructions.................................................................................................................................. ii
Proper use............................................................................................................................................... ii
Product disposal...................................................................................................................................... ii
General instructions................................................................................................................................ ii
Europe..................................................................................................................................................... ii
Deployment of ELPRO products in customer environment.................................................................... ii
Product Notices...................................................................................................................................... iii
󱛻󱛼󱛽ATTENTION................................................................................................................................... iii
Safety notices......................................................................................................................................... iii
󱛻󱛼󱛽CAUTION....................................................................................................................................... iii
Avoid ...................................................................................................................................................... iii
FCC notice .............................................................................................................................................. iii
ERT-A2 Overview.....................................................................................................................................1
Introduction ........................................................................................................................................1
Operation............................................................................................................................................1
Networking..........................................................................................................................................2
Ordering Guide........................................................................................................................................3
Model Overview..................................................................................................................................3
Accessories..........................................................................................................................................5
Installation ..............................................................................................................................................7
Enclosure.............................................................................................................................................7
Rain Tree/Standpipe Install.............................................................................................................8
Installation ..........................................................................................................................................8
Grounding .......................................................................................................................................8
Sensor Input Connections.................................................................................................................10
Digital or Pulsed inputs .................................................................................................................10
Analog inputs ................................................................................................................................10
SDI-12 Sensor Input.......................................................................................................................11
Connections (Milspec) ......................................................................................................................11
Rain (Digital)..................................................................................................................................11
River Digital (Digital/Pulse) ...........................................................................................................11
River (Analog)................................................................................................................................12
Solar (Ext Supply) ..........................................................................................................................12

ERT-A2 ALERT2 Configuration Manual
Revision 1.0
vi
Serial (Serial / SDI-12) ...................................................................................................................13
Connections (Terminals) ...................................................................................................................13
Rain (Digital)..................................................................................................................................14
River Digital (Quadrature or Incremental)....................................................................................14
River (Analog)................................................................................................................................14
Solar (Ext Supply) ..........................................................................................................................14
Serial (Serial / SDI-12) ...................................................................................................................15
System Design.......................................................................................................................................16
Unit type overview............................................................................................................................16
Field Station ......................................................................................................................................16
Repeater Station ...............................................................................................................................17
Base Receiver Station........................................................................................................................18
Repeater Station –Full Duplex High Capacity...................................................................................18
Repeater Station –Multi-Frequency or A1 Migration......................................................................19
Unit Configuration ................................................................................................................................21
Connecting to Menu .........................................................................................................................21
Configuration Quick Start Guide.......................................................................................................23
Quick setup ALERT2 ......................................................................................................................24
Quick Setup ALERT (Version 1)......................................................................................................24
Communications Configuration ........................................................................................................24
Integrated Radio Communications Configuration ........................................................................24
Cellular Communications Setup....................................................................................................26
4G/LTE Primary Communications Operation................................................................................28
RS-232 Reporting ..........................................................................................................................29
RS232 Serial Manu ........................................................................................................................29
Configuration ALERT Quick Setup.....................................................................................................29
Sensor Inputs Configuration .............................................................................................................32
Discrete/Digital Input setup..............................................................................................................34
SDI-12 Smart Sensor Configuration ..................................................................................................37
Diagnostics............................................................................................................................................39
Configuration Menu Items................................................................................................................39
Set factory defaults...........................................................................................................................40
OK LED Red Status Internal register bits decoder.............................................................................40
Radio Firmware Update....................................................................................................................41
Cellular Modem Force Update Messaging........................................................................................41
Firmware upgrade.............................................................................................................................43

ERT-A2 ALERT2 Configuration Manual
Revision 1.0
vii
Data log File download .....................................................................................................................43
General Specifications...........................................................................................................................44
Communications Channel Specifications..........................................................................................46
C1, C3 or C4 Condor Radio - Internal............................................................................................46
4G/LTE Cellular Integrated Gateway Router.................................................................................47
External Satellite Iridium Short Data Bust Modem - Integrated...................................................47
Accessories........................................................................................................................................48

ERT-A2 ALERT2 Configuration Manual Revision 1.0
1
ERT-A2 Overview
Introduction
The ERT-A2 (ERTA2) battery powered wireless environmental monitoring unit is designed to provide
reliable monitoring of environmental measurements in critical applications such as flood warning
and other disaster management applications.
Input sensors to monitor environmental conditions such as rainfall, river heights, wind speed, wind
direction, air temperature, humidity can be connected directly to the ERTA2 unit which will sample
these inputs and on a detected change of value send over VHF/UHF radio, cellular or satellite
networks.
The ERTA2 is a compact and highly integrated unit which includes the capability to sample sensor
inputs, manage battery power consumption, power supplies, MPPT smart solar regulator and one or
two communication channels. All this functionality in enclosed in a weatherproof IP66 enclosure
which can easily be installed directly outdoors, in a flood warning tree (standpipe) or in another
enclosure with other monitoring equipment.
Communications protocol used in the ERTA2 is ALERT2 which is an international industry standard
for flood warning and disaster management applications. ALERT2 offers benefits of allowing very
large numbers of field sensors to be support, very high level of data transmission reliability with data
encoding and forward error correction, and flexible sensor data types/engineering units.
Cyber Security has been a strong consideration in the design of the ERTA2 unit. Features have been
incorporated into the ERTA2 to provide effective device security. ELPRO continues to provide
additional security features to the product as they become available in new additionas of the ALERT2
protocol
The ELPRO ERTA2 unit provides an extremely versatile and feature packed unit allowing standalone
installations with the addition of only sensor connections and possibly a battery charging source
such as solar panel.
Operation
The ERTA2 unit is designed with features to allow the minimum power consumption to maximise the
operational battery life.
In normal operation the ERTA2 will be switching between sleep and awake modes to allow it to
sample sensor and internal inputs to detect changes. If nothing has changed then it goes back to
sleep. If there is a change then it will wake fully to send the changes over the communications
channel.
To conserve the units power consumption the frequency of communications transmissions should
be kept to a minimum. Sensor digital and analog inputs have a sensitivity value that can be
configured that is the threshold of change before a communications transmission will be triggered.
There is also a configurable paralysis time which will limit the frequency of transmissions. This is
configured value in seconds to wait before transmitting again.
The ERTA2 includes a wide range of internal diagnostics and internal inputs that can be configured to
send as ALERT2 messages. Internal inputs include battery voltage, power supply/solar voltage,
received signal strength (RSSI), internal temperature and internal status bits.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
2
Networking
Up to two internal communication channels are available. Primary channel supports VHF/UHF radio,
4G/LTE cellular or satellite networks. The secondary channel provides a redundancy mode and
supports cellular 4G/LTE and satellite.
Operational mode of the ERTA2 unit can be configured to either Field Station, Repeater or Base
Receiver when using primary VHF/UHF radio. The unit is also able to operate as a field station using
4G/LTE Cellular or Satellite primary radio.
Figure 3: Example: Typical system diagram with mix of ALERT2 and legacy ALERT1 equipment.
ALERT2 protocol can be configured for Field Station, Repeater or Base Receiver modes. Legacy
ALERT (ALERT1) can be configured for only Field Station and Base Receiver modes of use.
Field Station is typically used for flood warning gauge sites or any other environmental monitoring
site and is the lowest power consumption configuration.
Repeater units will store and forward communication messages from other Field Stations and/or
Repeaters to increase the maximum transmission distance. Repeaters units include ability to
configure station address whitelist/blacklist filtering to limit communications traffic in the network.
Base Receiver collects all the network communication messages directly from Field stations or
Repeaters and transports them to the Decoder-Gateway which provides protocol or media
conversion as required to data collection network.
Primary 5W
VHF/UHF/
Cell IIOT
Secondary
25W RF PA
/Cell/Sat
Communication
Options
A2 VHF
Repeater or
Base Rx’er
Internal
RS232 A2
Redundant Comms
Gateway
Internal
Cell/Sat
Figure 2: ERTA2 provides options for primary and
secondary communications
Figure 1: Redundancy available using secondary
communications with 4G/LTE Cellular or Satellite
networks

ERT-A2 ALERT2 Configuration Manual Revision 1.0
3
Figure 4: ERTA2 Receiver and 115U-2-A2 Decoder-Gateway including connectivity to include ALERT1 data conversion to
ALERT2 or industrial protocols Modbus/DNP3.
For more information on configuration of modes and features described above see relevant sections
of this user manual below or refer to ELPRO web site for additional application notes.
Ordering Guide
Model Overview
The ERT-A2 can be delivered as several different models and/or options. To identify the correct
model and options that you have, first locate the compliance label, which is located inside the unit
on the side opposite to the battery (if fitted).
The compliance label will look like the sample below but may have difference due to sales
region/model.
The standard ERT-A2 will supports ALERT2 operation as a field station, repeater or receiver base
station receiver through software configuration.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
4
To decode or specify product ordering code use the table below:
Part Number
EL-ERT-A2
-C
G
R
-X
A
Base Config
Enclosure
ERRTS Std Mil Spec
-M
Cable Gland
-C
1/2" NPT
-N
ALERT1 Upgrade Kit
-U
GPS
Fitted
G
Not Fitted
X
Battery
Internal rechargeable
R
Internal non rechargeable
P
External
E
Primary
Comms
Licence Free/Licenced
150MHz 5W
-1
300MHz 10W
-3
400MHz 10W
-4
500MHz 10W
-5
150MHz 25W
-H
Not Fitted
-X
Secondary
Comms
Cellular 4G LTE Gtwy
APAC
A
Americas
U
Europe
E
Satellite Gateway
Sat
S
Not fitted
Blank
X
Order model guide Notes:
•Not all possible build options above are available for order. Please check with your ELPRO
supplier.
•Example: Cable gland, internal rechargeable battery, secondary AU cell radio, EL-ERT-CXR-
XA
•All models with primary VHF/UHF radio -1, -3, -4, -5 and -H require GPS option for ALERT2
TDMA operation.
•Cellular/Satellite options do not require GPS option, time clock sync performed through
cell/sat network
•150MHz 25W Power Amplifier (PA) option will not allow secondary communications Cellular
or Satellite gateway fitment in single enclosure. If Cellular or Satellite gateway is required
with 25W PA option, then the gateway unit is ordered separately as a standalone IP
enclosure with RS232 link to ERT-A2 unit.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
5
Accessories
Application
Order Code
Description
USB programming Cable
CBLUSB-ATOB
USB 2.0 CABLE - TYPE A to TYPE B, 1M LONG
(Used to configure 115E/215/415/915U units).
RS232 to RJ45 serial cable
for 115E-2 gateway-decoder
CBLSER-RJ45
Serial Cable RS-232: 0.9m (3ft) long, RJ45(male)
to DB9(female) - Straight-through.
Installation in standard tree
(standpipe)
BR-ERTA2-TREE
ERT-A2 Tree mounting bracket including
hardware
Installation on vertical or
horizontal pole
BR-ERTA2-POLEMNT
ERT-A2 Pole mount kit, Horizontal or vertical
positions, Aluminium plate and hardware
Solar Installation
BR-SOLPAN10W
Solar Panel Pole Mount suit 5-10W
Antenna Surge Protection
SURCSD-N-6000MF
Coaxial Surge Divertor, Bulkhead N Female to N
Male DC-6GHz 30W WITHOUT earth tail
Antenna Surge Protection
SURCSD-N-6000
Coaxial Surge Divertor, Bulkhead N Female to N
Female DC-6GHz 30W WITHOUT earth tail
Antenna field station or
repeater
ANTB000100
VHF 3 dBd collinear - ‘N’ Type Female connector
Antenna bracket for
ANTB000100
ANT-BR-COL-KIT
Mounting Bracket Kit for Collinear Antenna
WITH 6 x VBLOCK and 2 x UBOLT5H
Antenna, low visual impact
ANTB000300
VHF Dipole Whip 3dB Antenna c/w 5M Coax N
type Connector
Supply with -xGx- option
above
ANTGPS-3-KIT
Weather Resistant IP67 GPS Antenna, 3m RG174
cable, SMA-Male with 16mm cable gland
Antenna cable assembly,
tree, pole or cabinet install
CC5-RG213
Coax Cable 5 Meters RG-213 terminated with ‘N’
connectors
Antenna cable assembly,
direct connect to ERTA2
CCTAIL-N-M
Coax Tail, 1000mm, RG-58, 'N' Male to 'N' Type
Male Connector
Antenna cable assembly,
pole or cabinet install
CC3-N
Coax Cable assembly, 3M Cellfoil, 'N' Male Type
'N' Male
Internal Battery:
rechargeable
BATS-ERTA2-LFP
Lithium iron phosphate (LFP), rechargeable high
power long life 3.0AHr battery for ERT-A2 pack
with cable and connector
Internal Battery: non-
rechargeable
BATS-ERTA2-LiP
Battery Holder: Customer supplied Lithium-
thionyl Chloride Primary (LiP), non-rechargeable

ERT-A2 ALERT2 Configuration Manual Revision 1.0
6
high power long life 5.8AHr battery pack, with
cable and connector
Solar Installation
ERT10WSOL
Solar power 10 watt panel, 3pin plug & Bracket
for Tree application
Solar Installation
SOLPAN10W
Solar Panel 12V PV Module 10W
AC power supply
PS-WW-XP-24DC-mm
AC Plug Pack Universal Input, 24V DC 1.25A
Output - AU wall plug

ERT-A2 ALERT2 Configuration Manual Revision 1.0
7
Installation
Enclosure
ELPRO ERTA2 electronics and battery are enclosed in a rugged IP66 rated cast Aluminium 190mm x
197mm enclosure with an opening/removable door.
Sensor and power connections are made through options for military specification screw-in
connectors (MilSpec) or through cable entry glands into internal industrial push connect wiring
terminals.
The MilSpec connectors are commonly used in flood warning applications. Connectors are pin
compatible with legacy ALERT1 ERRTS equipment to allow interchangeability in existing installations.
The enclosure is suitable to be installed in a variety of situations such as outdoor, indoor and cabinet
installations and has the ability to be secured with padlock if required.
Mounting options are
•Standard panel mounting via M6 mounting Holes 176mm x 119mm
square provide by integrated mounting feet on the enclosure
•Pole or Rail (horizontal or vertical) mounted using an ELPRO supplied
aluminium mounting plate (part no. BR-ERTA2-POLE ) and either
standard U clamps or s/s cable ties.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
8
Rain Tree/Standpipe Install
If the ERTA2 is to be mounted in a Tree, there is an aluminium
accessory holder that allows the Radio and a battery to be housed on
the plate that can then be lowered into the tree enclosure similar to
the older Legacy cannister.
Tree bracket provide facility to restrain sensor cables, carry handle
and location to connect rope or carabiner to secure the unit inside the
rain tree.
Installation
Grounding
To provide maximum surge and lightning protection for antenna connection and sensor inputs, each
module should be effectively earthed/grounded via a GND terminal on the module. This is to ensure
that the surge protection circuits inside the module are effective.
If the ERT-A2 is to be mounted in an enclosure you need to ensure the enclosure ground and the
antenna mast/pole ground are connected to the same common ground point.
The ERT-A2 have a dedicated earth/ground connection M5mm screw on the side of the enclosure
for this Earth connection. All earth/ground wiring should be minimum 0.8 in2 (2 mm2), 14 AWG.
Earth screw MAX length is 8mm.
Figure 5: Earth Screw Location.
When installing the unit, it is important to ensure what all antenna cable
connections are waterproofed as water ingress into the cable will affect its
performance.
See below for recommend installation.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
9
Figure 6: Recommended installation earthing for outdoor installation
Note: When installing into a Tree (standpipe) enclosure, the grounding is provided by the antenna
connection and the tree installation. No additional ground connection is required.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
10
Sensor Input Connections
The ERTA2 unit can be connector to several different types of external sensor inputs such as discrete
on/off, pulsed, 4-20mA analog and SDI-12, allowing a large number of different sensors to be
monitored in a single installation.
There are several internal sensor inputs to allow diagnostic data to be transmitted or logged for
battery health, power supply or solar, communications status and internal temperature.
Type
Number
Configurations
Discrete
4
Pulsed, ON/OFF or encoder configurable
Analog
2
4-20mA
SDI-12
1 Channel
Up to max of 52 sensors and/or variables
Internal
4
Battery Voltage, Supply/Solar Voltage, Radio Received Signal
Strength, Internal Temperature, Internal Status
The ERTA2 is available in two enclosure options for support different types of installations. Mil Spec
connector enclosure provides a compatible connection with existing tree installations.
Cable gland enclosure option is available for installations where the Mil Spec connections are not
required and is a very good option for outdoor pole mounting, elevated platforms or cabinet
installations.
Digital or Pulsed inputs
Digital Input channel 1 & 2 on the module modules can be used for a digital ON/OFF signal, a pulsed
signal from something like a Tipping Bucket Rain Gauge, or a Shaft Encoder for measuring level.
In normal flood or environmental gauging applications digital Input 1 & 2 are used for a shaft
Encoder. Shaft Encoders translate the rotation of an input shaft into a digital signal which can be
read in the ERT-A2 inputs. A float connected to a beaded line over a pulley causes the shaft to rotate
as it rises and falls with river level. Shaft encoders generally use some sort of "stilling well" in the
river so that waves on the surface of the river do not cause the encoder to continually fluctuate. The
ERTA2 unit supports incremental or quadrature type shaft encoders.
Digital Input 3 is a Pulsed input signal only, normally used for a Tipping Bucket Rain Gauge (TBRG)
providing a dry contact closure through a small magnetic switch triggering for each increment of rain
fall. Maximum Pulsed input rate is 10Hz
Digital Input 4 can only be used as Digital ON/OFF input, which could be used for a limit switch or
intruder alarm.
The digital inputs whether a pulse, ON/OFF switch or encoder are activated by connecting the input
terminal to GND or common, either by voltage free contact, TTL level, or transistor switch.
Analog inputs
The module provides two floating differential analog inputs capable of measuring 0-24mA for 4-
20mA transducers/sensors.
It should also be noted that the analog inputs can also be used to connect single ended current
sinking or sourcing devices and can be connected in top or bottom of the analog loop.
The module also provides a switched 24V Analog Loop Supply (ALS) with a maximum of 50mA for
any single ended current loops. To get the best battery life performance the ALS can be configured

ERT-A2 ALERT2 Configuration Manual Revision 1.0
11
in the ERTA2 unit to only turn on during the sample period and can also provide a sensor warmup
time before sampling the analog value.
The 4-20mA signal is normally used for measuring river level using a pressure transducer which
detects water pressure at the riverbed or from a bubbler system which uses a constant flow of gas
through a pipe to the water level. As the river level rises, the water pressure at the riverbed
increases. The 4-20mA signal can also be used other types of sensors such as flow, temperature, etc.
SDI-12 Sensor Input
Smart sensors can be connected using the SDI-12 input which can support a single channel with up
to 52 sensors/variables.
SDI-12 is a three-wire serial sensor bus and allows reading of a number of variables from each sensor
on the bus, which can be configured and reported by the ERTA2 unit. Connection to the SDI-12 bus
can only be made directly to internal terminals or through the 6-way “serial” Mil Spec connectors.
SDI-12 connectivity is shared with the RS-485 communications channel and is not available if the unit
is configured as a base receiver.
Connections (Milspec)
Rain (Digital)
The Rain input connector on the ERT-A2 is for connecting a
Tipping Bucket Rain Gauge (TBRG), which should be
connected to pin “B” (Common) and “A” (Input).
River Digital (Digital/Pulse)
Shaft encoders connector allows for connection of a shaft
encoder.
The ERT-A2 provides supports both Incremental and
Quadrature type encoders which is selectable in software
configuration.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
12
River (Analog)
Externally Powered devices can be connected directly
to the AIN+ & AIN- connection pins.
If connecting to a single ended device, then the module
can provide the +24V Loop supply and will need to be
connected as per the diagram.
Solar (Ext Supply)
The Solar connector allows for the connection of a 5-30W
solar panel connection or an external 24W power supply to
power or charge the internal / external battery.
Warning: The solar input is suitable for solar panels rated
as 12V nominal only. 24V solar panel can produce open
circuit voltages of 44Vdc which will exceed the rated input
of the solar regulator and cause damage.

ERT-A2 ALERT2 Configuration Manual Revision 1.0
13
Serial (Serial / SDI-12)
The Serial connector has the communication connections
for RS232 and SDI-12 (Mil Spec connections not available
with Cellular or Satellite communications options).
•RS232: Used for connecting to the unit for
configuration/diagnostics in legacy applications or for an
alternate ALERT2 communications output port.
•SDI-12: Communication bus for SDI-12 smart sensors
or devices.
Note: RS485 and SDI-12 cannot be used at the same
time.
For units which include primary or secondary cellular or satellite communications the RS-232 port is
used.
The Mil Spec connector will provide connections for SDI-12 and RS-485 (receiver base or migration
unit ALERT concentration messages).
Serial input connector provides for RS-485 ALERT2 or
ALERT1 concentration for receiver base configurations.
SDI-12 smart sensor can be connected to this input if used.
Note that SDI-12 and RS-485 cannot be used together.
Connections (Terminals)
The ERTA2 weatherproof enclosure is available with two connection options, Mil Spec and cable
gland. When using the cable gland option all wiring connections are made directly into internal
terminals through weatherproof glands.
In some applications customers may prefer to use the internal wiring connectors rather than the
external Milspec connectors. This may be for ease of installation, or to allow access to additional
functionality not available through the Milspec connections.
In this case one or more of the Milspec connectors can be removed and replaced with an M20 cable
gland to allow direct cable entry to the module. When removing the Milspec connector take care to
re-install the M4 mounting screws into the case to maintain a watertight seal.
Units are shipped with a cable gland to allow the swap out of Mil Spec connector for direct wiring.