mPower Electronics VOXI User manual

VOXI
Fixed Photo-ionization Detectors
MP812 & MP815
User’s Guide
Rev 0.4
October, 2019

VOXI User’s Guide
1
Contents
1. General Information ............................................................................................... 5
1.1 Key Features........................................................................................................................................................5
2. User Interface.........................................................................................................6
3. Installation .............................................................................................................7
3.1 Mounting ............................................................................................................................................................7
3.2 Rain Cap ..............................................................................................................................................................8
3.3 Electrical Connections .........................................................................................................................................9
3.3.1 Baseline 4 mA Signal Adjustment ..................................................................................................................10
3.3.2 MODBUS Message RTU Framing ...................................................................................................................10
4. Operation Overview ............................................................................................. 11
5. Controller Operations ........................................................................................... 11
5.1 Hardware and Software Requirements.............................................................................................................11
5.2 Connecting the VOXI to the Controller (Mobile Device)....................................................................................12
5.3 Operation Shortcut Buttons and Overview .......................................................................................................12
5.4 Field Service (Calibration, etc.)..........................................................................................................................13
5.5 VOXI Settings ....................................................................................................................................................16
5.6 View Operations Log.........................................................................................................................................17
6. Maintenance ........................................................................................................ 18
6.1 Replacing Filters................................................................................................................................................18
6.2 Removing/Cleaning/Replacing Lamp and Sensor .............................................................................................18
6.3 Replacing Pump ................................................................................................................................................20
7. Troubleshooting ................................................................................................... 21
8. Technical Specifications ........................................................................................ 22

VOXI User’s Guide
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Read Before Operating
This manual must be carefully read by all individuals who have or will have the responsibility of
using, maintaining or servicing this product. The product will perform as designed only if it is
used, maintained and serviced in accordance with the manufacturer’s instructions. The user
should understand how to set the correct parameters and interpret the obtained results.
WARNINGS !
•Never operate the monitor when the cover is removed.
•Remove the monitor cover only in an area known to be non-hazardous.
•Use only mPower’s sensor and accessories. Substitution of components will impair
suitability for intrinsic safety and void warranty.
•The instrument should be calibrated after installation before initial use and checked by
exposing it to a known concentration calibration on a regular basis.
•Ensure that the gas inlet is not blocked.
•Make sure that all filters are clean and replaced on a regular basis.
•Remove the sensor only if necessary for repair. Zero and span calibration are required once
the sensor is moved.
Special Conditions for Safe Use
The VOXI monitor must be calibrated if it does not pass a bump test, when a new sensor has
been installed, or at least once every 180 days, depending on use and sensor exposure to poisons
and contaminants.

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1. General Information
The VOXI is one of the most advanced fixed monitors available for ppb (parts per billion)
detection of VOC (Volatile Organic Compound). It operates on 12-30 VDC power and provides
various outputs including OLED digital read-out, 4-20 mA analog output, RS-485 digital output,
CAN or Modbus, 3 relays, and one port to an external strobe or horn. The VOXI offers
two models that measure from low ppb to a high range up to 5000 ppm for different applications.
Novel designs of the photo-ionization detector (PID) and ultraviolet (UV) lamp provide
outstanding sensitivity, stability and reproducibility. An on-board heater prevents condensation
at low temperatures. Configuration and testing is performed conveniently using a mobile App
and Bluetooth controller. Options include real time remote monitoring with a built-in wireless
modem using mPower Suite application software.
1.1 Key Features
•VOC emissions monitoring using innovative PID for performance & long life
•700 integrated gas correction factors
•0.001-200 ppm (MP812) and 0.01-5000 ppm (Mp815) ranges of VOC
•Outstanding linearity over full measurement range
•Auto-ranging and auto-zeroing
•5-second response time for 90% change (using isobutylene)
•Built-in pump for up to 30 meters sampling distance
•Size: 8.4 x 7.1 x 5.0 in (213 x 180 x 127 mm)
•Weight: 3.3 lbs. (1.5 kg)
•12-30 VDC power input
•OLED display for maximum visibility outdoors
•3 Relays, 4-20 mA, RS-485 and output to alarm strobe or horns
•Mobile App and Bluetooth controller for handy configuration and testing
•Wide temperature range of -40° to +70°C (-40° to 158°F) with built-in heater to prevent
condensation
•Rugged, explosion-proof housing with IP-66 rating
•Real-time remote wireless monitoring and alarm notification option

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2. User Interface
The VOXI user interface consists one large OLED Display showing the gas concentration, one
status LED, two alarm LEDs, and various status icons. Calibration and other parameters are
programmed using the mPower Suite mobile App on a smart-phone or tablet.
Status
LED
Low
Alarm
LED
High
Alarm
LED
Power Supply,
Alarm, and Data
Output Wires
Electrical
Ground
Connector
Secondary Filter
(Inside Housing)
Water Trap
Filter
Gas Inlet
Wireless Signal
Strength
Bluetooth
Connection
Pump Status
Gas
Concentration
Unit
Concentration
Read-out
Measured Gas
Selection
Gas Outlet
Rain Cap
Lock Screw

VOXI User’s Guide
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3. Installation
WARNING !
•The VOXI is currently not certified for use in hazardous gas locations. Install this unit only
in an area known to be free of combustible gases and vapors.
•Before installation, ensure that all power is disconnected.
•Before removing the monitor cover for service, disconnect the power supply and ensure
that the area free of combustible gases and vapors.
•For European locations, installation must comply with EN-60079-14.
•The instrument should be calibrated after installation before initial use and checked by
exposing it to a known concentration calibration on a regular basis.
•Remove the sensor only if necessary for repair. Zero and span calibration are required once
the sensor is moved.
3.1 Mounting
3.1.1 Mounting Location
For safety and ease of maintenance, the VOXI should be installed in a non-hazardous-gas
location.*
1
Extension tubing of up to 100 feet (30 m) can be attached to the inlet to allow remote
mounting if the sampling location contains flammable or toxic gas mixtures.
3.1.2 Mechanical Mounting Options
The VOXI is designed for wall mount or pole mount using the screw-holes provided, centered
5.25 inches or 134 mm apart. If mounted outdoors, ensure that the gas inlet is directed
downwards to minimize the chance of precipitation being drawn into the PID.
*
1
Future VOXI versions that have certifications will be able to be installed and operated in hazardous-gas
locations, but because the housing cannot be opened for service in the presence of flammable gases, the VOXI is
easier to maintain if installed in a non-hazardous location or one that can be vented to remove hazardous gases
before opening the housing.

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An optional mounting bracket (P/N M008-3004-000) is available that allows the unit to be offset
about 1 cm from the wall or pole.
3.2 Rain Cap
If mounted outdoors, the rain cap can be installed to further reduce the chance of precipitation
ingress. This cap also allows connection of tubing to the gas outlet if it is desired to vent the
exhaust away from the VOXI instrument.

VOXI User’s Guide
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3.3 Electrical Connections
Two conduit holes are provided in the explosion-proof housing, one covered by a hex-head plug
and the other for wire connections. To unscrew and remove the cover, first loosen the lock screw
located on the side, using a Allen wrench. Pinch the buckles on both sides of the instrument
assembly to release and then lift it out. Unplug the three terminal block plugs on the PC board.
The schematic below shows the internal wiring connections. Insert the wire through the conduit
hole and connect to the corresponding pin numbers of the three terminal blocks on the bottom of
the assembly. These blocks accept 12AWG to 24AWG wire (0.2 to 4.0 mm2). Input power
requirements are <5W, 12-30 VDC. An external ground wire (AWG11 recommend) must be
connected to the VOXI housing reliably.
Terminal Blocks
Terminal
Block
Plugs
Lock Screw

VOXI User’s Guide
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3.3.1 Baseline 4 mA Signal Adjustment
If sending the 4-20 mA signal to a remote controller, during the field installation the VOXI
analog output should be adjusted. See VOXI Field Service section below for procedures.
3.3.2 MODBUS Message RTU Framing
The VOXI uses RTU framing for MODBUS messages. The following is an excerpt of the
MODBUS over Serial Line Specification and Implementation Guide v1.02 (Dec.2006) with more
information available at http://www.modbus.org/ and http://www.modbus.org/specs.php :
A MODBUS message is placed by the transmitting device into a frame that has a known beginning and
ending point. This allows devices that receive a new frame to begin at the start of the message, and to
know when the message is completed. Partial messages must be detected and errors must be set as a
result. In RTU mode, message frames are separated by a silent interval of at least 3.5 character times.
In the following sections, this time interval is called t3,5.
RTU Message Frame
The entire message frame must be transmitted as a continuous stream of characters. If a silent interval of
more than 1.5 character times occurs between two characters, the message frame is declared incomplete
and should be discarded by the receiver.
Remark : The implementation of RTU reception driver may imply the management of a lot of interruptions
due to the t1.5 and t3.5 timers. With high communication baud rates, this leads to a heavy CPU load.
Consequently these two timers must be strictly respected when the baud rate is equal or lower than
19200 Bps. For baud rates greater than 19200 Bps, fixed values for the 2 timers should be used: it is
recommended to use a value of 750 µs for the inter-character time-out (t1.5) and a value of 1.750 ms for
inter-frame delay (t3.5)

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4. Operation Overview
Once installed and power is turned on, the VOXI runs continuously to measure VOCs, display
the concentration readout and any alarms (flashing LEDs), and send any output and alarm signals
connected to external devices. The pump runs intermittently when VOCs are below 500 ppb, in
order to extend the life of the filters and the pump itself, but runs continuously above this
threshold. The VOXI has an on-board heater which turns on at low temperature to reduce the
possibility of condensation in the PID sensor. Both the VOC threshold and temperature threshold
are set at the factory and cannot be adjusted by the user. Other operating parameters are set with
the controller.
5. Controller Operations
5.1 Hardware and Software Requirements
An external mobile phone or tablet is required as a controller to program operating parameters.
Currently Android 6.0 or higher platforms are supported. Updating to the latest Android version
is common practice and recommended. Use an Ex (Intrinsically safe) Android device if operating
in hazardous environments. Operation requires the mPower Suite Android App. If not already
installed, it can be downloaded at https://www.mpowerinc.com/software-downloads/ . The
Controller allows users to:
•Get and set VOXI configurations
•Perform calibrations
•Adjust the analog 4-20 mA output baseline
•Adjust the pump stop threshold
•Join an mLink wireless system
5.1.1 Supported Languages
English and Chinese.