EVO Power, Meter & Sensor Connections

The Outpost EVO is designed to operate from any suitable 5-35V DC source and has the following meter & sensor interfaces available:

• 3 x “Current Loop” (mA) inputs for 4-20mA or 0-20mA sensors
• 2 x Counter (pulse) inputs with fast and debounce mode selection
• 1 x 2-wire Digital interface port selectable between “3-wire” RS232 and “half-duplex” RS485
• 3 x Switched Power Output (SPO) ports (internally common) for momentarily powering external sensors
• 1 x NTC Thermistor Input (Channel 3 mA input is optionally switchable to NTC thermistor mode)

The following sections show the Outpost EVO terminal block connections, and details on how to connect different meter & sensor types.

It is recommended that you attach any inputs to the terminal blocks first, and then connect the power source.

 

General Connections

Outpost Evolution interface with a pulse output meter

 

Terminal Block positions – Input End:

SPO	Provides a 15V DC power output, switched on during Logging mode. This is typically used to provide power to analogue input devices.
SPO	Provides a 15V DC power output, switched on during Logging mode. This is typically used to provide power to analogue input devices.
GND	Ground (Typically used for Analogue Input 2 ground)
AIN2	Analogue Input 2 (4-20mA in standard model, resistance input in WTH variant)
GND	Ground (Typically used for Analogue Input 1 ground)
AIN1	Analogue Input 1 (4-20mA)
GND	Ground (Typically used for Pulse Input 1 ground)
COUNT1	Pulse Input 1
GND	Ground (Typically used for Pulse Input 2 ground)
COUNT2	Pulse Input 2

 

Terminal Block positions – Power End:

VDC (5-38V)	Connect to DC power source (positive)
GND	Connect to DC power source (negative)
TX/Data(+)	Transmit / Data+ for Serial Input (selectable RS232 or RS485)
RX/Data(-)	Receive / Data- for Serial Input (selectable RS232 or RS485)
GND	Ground (Typically used for Analogue Input 3 ground)
AIN3	Analogue Input 3 (Selectable as 4-20mA or Temperature)
SPO	Provides a 15V DC power output, switched on during Logging mode. This is typically used to provide power to analogue input devices.
GND	Ground (Typically used for Analogue Input 3 ground)

 

Power Connections

The Outpost Evolution can be powered from any 5-35V DC power source which is capable of delivering at least 400mA @ 12V.

Inputs and Power should be connected according to Figure 3. It is recommended that you attach any inputs to the terminal blocks first, and then connect the power source.

EVO hardware versions EVO_RevC and earlier can be damaged by connection to Lead Acid chemistry batteries with total voltage over 20V+ due to inrush current voltage spikes. Do not connect more than 1 SLA battery is series to EVO_RevC or older versions.

 

General Pulse/Counter Connections

Any sensor with “voltage free” contact closure can be interfaced with the Outpost Evolution.  A Normally Open circuit will give a slightly longer battery life, due to a Normally Closed circuit constantly drawing a small current between pulses. The Outpost Evolution will power the circuit with 3.0 Volts and it is preferable to have as short a cable run as possible.

The Outpost Evolution Pulse-Input detects a pulse in the form of a closed circuit from the output of the meter. The meter output can be a passive switch (e.g. Reed Switch) or electronic switch (e.g. opto-isolated transistor). Because electronic switches may not be a perfect closed circuit, the Outpost makes an allowance for this condition. The switch or transistor must have no more than 1.5V voltage drop across it with the Outpost attached, for the Outpost to register a pulse.

 

   

Interface with a pulse output meter

 

There are generally 2 different types of pulse output sensors available:

• Magnetic reed switch

A common sensor interface is a magnetic reed switch and it does not matter which way around you connect the 2 wires to the Outpost Evolution Pulse Input (Connection is not polarised)

• Transistor / Opto-isolated Output

Some meters may have a transistor or Opto-isolated pulse output.  It does matter which way round you connect this type of meter to the Outpost Evolution Pulse Input. (I.e. Connection is polarised.) The COUNT1 terminal is +ve 2.8V, and the GND terminal is Ground. Refer to the sensor or meters documentation for polarity and wire core colour. 

 

Pulse/Counter Input Mode

The Outpost Evolution can be configured in 2 different input modes to suit different sensors/meters.

• Debounce – Usually used with Magnetic Reed Switch sensors, where the mechanical action of the sensor causes small false pulses adjacent to the actual pulse. The debounce mode filters any false pulses, but has a maximum pulse frequency of 5Hz.

Interface with a dry-contact reed switch

 

• Fast-Pulse – Usually used on transistor output or opto-isolated meters, where a high frequency clean pulse is generated. The Outpost Evolution can register pulses up to 3kHz in this mode.

Interface with transitor output meter

 

Pulse frequency limit:
Input Open-Circuit Voltage
Input Closed-Circuit Voltage threshold
Input protection	30V DC

The modes are selected by adjusting 2 switches on the main circuit board inside the case, as per the diagram below.

 

Pulse Input Mode selection (photo shows debounce mode selected)

 

Current Loop (mA) & Thermistor Inputs

“4-20mA” is an standard electrical interface used in millions of sensors around the world that allows sensors to communicate their measurements to a controlling/monitoring device. Sensors that use “4-20mA” measure variables such as temperature, tank level, pressure, soil moisture and many more.

Any 4-20mA analogue sensor can be connected to Analogue Inputs 1, 2, and 3 on the standard Outpost EVO “EVO-2G-STD” device.  EVO variants can accommodate 4-20mA inputs according to this table:

EVO Product Code	4-20mA Channels	Resistance / NTC Thermistor Channels
EVO-2G-WTH	1 3 (must select)	2 3 (must select)
All other EVO variants	1 2 3 (must select)	3 (must select)

4-20mA “loop-powered” sensors can be powered by either:

• Switched Output (SPO) channel on the Outpost EVO
• External power source

 

Powering 4-20mA Sensor from Switched Power Output

To connect a loop powered 4-20mA sensor to the EVO and power it from the EVO SPO, connect the “power” (+ve) wire from the sensor to the “SPO” channel on the EVO and the “signal” (-ve) wire from the 4-20mA sensor to any AIN input on the Outpost EVO.

 

4-20mA loop powered sensor powered by EVO SPO

 

4-20mA loop powered pressue sensor powered by EVO SPO
(Note: pressure sensor earth wire not connected)

 

Powering 4-20mA Sensor from External Power

To connect a loop powered 4-20mA sensor to the EVO and power it from an external power source, connect the “power” (+ve) wire from the sensor to the external power source directly and the “signal” (-ve) wire from the 4-20mA sensor to any AIN input on the Outpost EVO.

You must ensure the external power source is rated properly for your 4-20mA sensor specification. Outpost central is not responsible an incorrectly specified external power source.

Figure below shows a 4-20mA pressure sensor powered from the same power source used to power the Outpost EVO, and returning the signal into channel AIN1.

 

4-20mA loop powered sensor powered from external power

 

4-20mA loop powered pressure sensor powered from external power

 

Resistance/Temperature Probe Input

If a temperature probe (thermistor) is used, it must be connected to Analogue Input 3, and the Analogue Input 3 Mode switch set on the circuit board.

Resistance output sensor connceted to EVO AIN3

 

EVO Analog input 3 (AIN3) switch position (Photo shows 4-20mA position selected)

 

1.1Serial (RS-232/RS-485) Inputs

The Outpost EVO has 1 serial port that can be used to attach serial interface meters & sensors, PLCs or expansion modules.

The Outpost EVO supports the following protocols on the serial port:

Serial Protocol	Notes
MODBUS	Standard MODBUS master
ADAM/NUDAM	Proprietary ADAM/NUDAM I/O expansion module, command response
Sentek (MODBUS)	Proprietary Sentek soil-moisture probe MODBUS transaction sequence
Aquaflex	Proprietary Aquaflex serial, command response

The serial port is selectable between RS-232 and RS-485 mode by changing internal jumpers.

 

Serial output port selection using jumper pins (photo shows RS232 selected)

Serial devices are attached to the Evolution through the TX/Data+ and RX/Data- terminals.

For RS485 serial connect your RS485 meter/sensor Data+ and Data- to your corresponding Tx/Data+ and Rx/Data- pins on the Outpost EVO.

For RS232 wiring connect your meter/sensor 9-Pin serial pin2 to Tx/Data+ and meter/sensor 9-pin serial pin3 to Rx/Data-. Refer to figure 11 for wiring detail. 

 

Meter/Sensor side: 9-pin RS232 connector pin-out

25-pin RS232 (DB-25) connectors are also supported please refer to your manufacturers documentation for corresponding Tx and Rx pinout.

 

3^rd Party Meter/Sensor Configuration Instructions

For further instructions on connecting selected 3^rd party meters/sensors & IO modules to the Outpost EVO refer to these sections:

ADAM-4017+                     Appendix A

Brainchild IO-16DI            Appendix B

For other 3^rd party meter/sensor, PLC or expansion modules refer to the manufacturer documentation for  more information on how to connect your device.