VOXI EC MP840

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 removed and re-inserted or replaced.

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.

1. General Information

The VOXI EC MP840 is a point-type toxic gas transmitter designed modularly with smart electrochemical sensor technology and an integral flameproof enclosure for fixed applications. The versatile platform offers more than 10 sensor options with auto-zeroing and offline calibration. Three-wire 4-20 mA analog and RS485 digital (for Modbus) signal outputs are standard. Three sets of programmable relays allow triggering of external alarms such as a siren or visual beacon. Various applications include oil & gas, petrochemical, chemical, metallurgical, pharmaceutical, semiconductor, environmental monitoring, and other industry facilities.

1.1 Key Features

• Selection of more than 10 chemical gas types
• Smart modules with sensor identification and manufacturing data
• Sensor diagnosis, temperature compensation and auto-zeroing
• LCD with backlight that changes color according to alarm condition
• Calibration due date notification
• 3 Wires for 4-20 mA and RS485 ModBus output
• Infrared remote programmer for settings, calibrations and adjustments
• Error codes for easy troubleshooting
• Recoverable factory settings
• Overrange protection, reverse polarity protection
• IP-67 rating
• IECEx certification

2. User Interface

The VOXI user interface consists of one large LCD Display showing the gas concentration, a power status LED, an alarm LEDs, and a fault indicator LED. Calibration is performed and operating parameters are entered using a handheld IR remote programmer.

Diagram shows the VOXI EC gas detector with labels pointing to: Conduit Portal for Wiring, Grounding Point, Mounting Slot, Sensor Location, Gas Inlet, Rain Cap, Alarm LED, Power LED, Fault LED, Gas Sensor Type, and Concentration Read-out. Another view shows the display changing color to indicate alarms or faults.

3. Installation

❗ WARNINGS !

• The VOXI EC has CNEX and IECEx certifications for use in hazardous gas locations. Check for certification requirements before installing.
• The VOXI EC has NO HAZARDOUS GAS CERTIFICATION when used with 16/3SOOW cable for oil and water.
• 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 gas on a regular basis.
• Remove the sensor only if necessary for repair. Zero and span calibration are required once the sensor is removed and re-inserted or replaced.

3.1 Mounting

3.1.1 Mounting Location

Because the VOXI EC samples by diffusion, it should be installed directly in the area to be measured.*1 For an entire room to be monitored, there is a reliance on good air circulation within the room, since the VOXI can only measure in the immediate vicinity of its inlet. If the VOXI must be mounted remotely, the gas must be pumped to the inlet because it has no sampling pump of its own.

3.1.2 Mechanical Mounting Options

The VOXI EC is designed for wall mount or pole mount using the screw-holes provided, centered 5.25 inches or 134 mm apart. An optional mounting bracket (P/N M024-3003-000) is available that allows the unit to be offset about 1 cm from the wall or pole. If mounted outdoors, ensure that the gas inlet is directed downwards and the raincap is installed to minimize the chance of precipitation entering the sensor inlet. The shape and dimensions of VOXI are shown in the figure below:

Diagrams show front and side views of the VOXI EC, illustrating wall and pole mounting configurations. Bracket dimensions are provided in mm and inches.

3.2 Rain Cap

If mounted outdoors, the rain cap should be installed to reduce the chance of precipitation ingress. If mounted indoors, the rain cap may be removed.

3.3 Electrical Connections

3.3.1 Internal Wiring

Four openings are provided in the explosion-proof housing, covered by hex-head plugs which can be removed to attach conduit for remote wiring, alarm beacon, antenna, and/or other wire connections. For internal connections, unscrew and remove the cover by first loosening the lock screw located on the side, using an Allen wrench. Pinch the buckles on both sides of the instrument assembly to release and then lift it out. Unplug the sensor plug from the PC board.

Schematic shows terminal blocks numbered 1-15. Terminal 1-5 are for Alarm High, Alarm Low, Alarm Fault, NC, and +V respectively. Terminal 6-8 are for Alarm High, Alarm Low, and Alarm Fault outputs. Terminal 9 is COM for relays. Terminal 10-12 are for RS485A, RS485B, and RS485 shielding. Terminal 13-14 are for 4-20mA OUTPUT and GND. Terminal 15 is +V. A relay symbol is shown connected to terminals 6-9.

3.3.2 Grounding

Two images show grounding points: one labeled 'Internal Grounding Point' inside the unit, and another showing 'External Grounding Points' on the housing.

3.3.3 Maximum Wiring Length

The maximum signal transmission distance can be estimated from the resistance of the shielded cable, allowing for a maximum of 150 Ω, as shown below (actual maximum distance may vary).

❗ WARNING !

The VOXI EC has NO HAZARDOUS GAS CERTIFICATION when used with 16/3SOOW cable for oil and water.

3.3.4 Baseline 4 mA Signal Adjustment

If sending the 4-20 mA signal to a remote controller, during the field installation the VOXI EC analog output should be adjusted. See VOXI EC Field Service section below for procedures.

3.3.5 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.

Diagrams illustrate MODBUS RTU framing, showing message frames separated by silent intervals (t3.5). Another diagram details the RTU Message Frame structure with Start, Address, Function, Data, CRC Check, and End fields. A third diagram shows frame timing (t1.5 and t3.5) for OK and NOK frames.

4. Operation

4.1 Standard Operation

Once installed and power is turned on, the VOXI EC cycles through a start-up sequence. After start-up, the VOXI EC samples the gas by diffusion and runs continuously to measure the toxic gas (or oxygen), display the concentration readout and any alarms, and send any output and alarm signals to external devices. When an alarm level is exceeded, the Alarm LED flashes and the display backlight changes color.

4.2 Programming using Hand-held Remote

Configuring and calibrating the VOXI EC is done using a handheld remote programmer. There is no magnetic key or other means of programming the VOXI EC directly. Communication with the transmitter functions from up to 3 m (10 ft) distance when directed straight at the transmitter display instead of from an angle.

❗ WARNING !

• VOXI EC monitoring is turned off during communication with external devices.
• Perform programming and calibrations only during times known to be free of toxic or combustible gases and vapors.

4.2.1 Battery Installation

The remote programmer uses a CR2025 3V battery or equivalent. To remove or replace the battery, place the unit face down, push the retaining hook inward and slide out the battery holder.

4.2.2 User Interface

Press the Main Menu Access button on the Remote Programmer to display the user interface on the VOXI LCD. Program operations can be selected using the cursor movement arrows. Shortcut operations can be conducted using the Zero and Span buttons to quickly perform routine zero and span calibrations. The firmware is factory-set and currently cannot be changed by the user.

Diagram of the handheld remote programmer shows buttons labeled 'Main Menu Access', 'Cancel', 'Confirm', 'OK', 'Left/Right Cursor Movement', 'Menu Up/Down Scrolling Number Increase/Decrease', 'Zero Calibration', and 'Span Calibration'.

4.2.3 Navigating Menus and Sub-menus

Press the Main Menu Access button and use the Up and Down arrows to scroll through the menu. Use the Right and Left arrows to enter or exit a menu item. When entering numerical values, use the Left or Right arrows to move the cursor, and the Up and Down arrows to increase or decrease the values. When the cursor is moved to the "?", press OK to save or enter. To exit a sub-menu, press the cancel key [cancel]. To exit the Main Menu, scroll down to the EXIT screen and press OK. The display will also automatically return to concentration readings after about a minute of non-use.

Diagrams illustrate menu navigation sequences: entering a menu, entering a password, scrolling through menus, and exiting a menu.

BASIC and ADVANCED Menus

There are two menus:

• Basic Menu is accessed using default Password 0000. This allows basic field operations such as calibration, setting alarm levels, and communication with PC for firmware upgrades.
• Advanced Menu is accessed using default Password 8888. This allows access to additional advanced features such as changing passwords, changing concentration units, setting location ID, etc.

The Basic Menu and sub-menus are listed below

The table below lists all Advanced Menus and their sub-menus.

Diagram shows a flow of menu selections for the Advanced Menu, starting from the main screen and progressing through options like PSWD, ALM, CAL, UNIT, BPS, 4_20, ASET, USID, STID, COMM, and EXIT.

4.2.4 Default Settings

#Default settings subject to change – always check instrument. *Check sensor availability.

4.3 Calibration

Diagram shows components for calibration: Calibration Cup, Zero or Span Gas Supply, and Rain Cap Alternative.

1. Before calibration, it is good practice to examine the inlet filter and replace as needed. 2. Zero Calibration: Scroll to the CAL ZERO menu. Alternatively, press the short-cut "Zero" button on the programmer. Supply clean air to the inlet. If the VOXI EC is mounted in an area where ambient air contains detectable concentrations of gases, attach the calibration cup and supply clean gas (air) directly from a cylinder fitted with a fixed-flow regulator of about 0.3-0.6 LPM. If no calibration cap is available, the rain cap may be used. Connect the zero gas directly to the rain cap. 3. For Oxygen sensors, the zero gas is ambient air (20.9% O2) and 0% O2 is set using pure N2 during span calibration (see below) 4. Click 'OK' to initiate the 30-second count-down timer, after which Pass or Fail is displayed. Click 'OK' to move to Span or continue to Exit. 5. To abort, press [abort] during the count-down.

Diagrams illustrate the Zero Calibration process using the remote programmer, showing menu selections and countdown timers. Another diagram shows the Span Calibration process.

5. Maintenance

The VOXI EC requires regular filter replacement and possibly sensor replacement if used in areas of high dust or condensation. Sensor life is typically 1-3 years depending on sensor type.

5.1 Filter Replacement

If the inlet filter is dirty or clogged, discard it and replace it with a new filter. Dirty filters can be recognized by symptoms such as:

• Visible filter discoloration
• Visible moisture accumulation
• Weak sensor response

We recommend filter replacement every month, and more frequently, possibly weekly, when used under very dusty or wet conditions. Remove the rain cap (if used) and unscrew the metal sensor housing. Remove the mesh screen and filter, replace the old filter with a clean one, and reassemble the mesh and sensor housing.

Image displays components for filter replacement: EC Sensor Module, Gasket, Inlet Filter, Mesh Screen, and Sensor Housing.

IMPORTANT! The VOXI EC should not be operated without a filter. Operation without a filter may damage the instrument and shorten the life of the sensor.

5.2 Sensor Replacement

❗ WARNING !

Replace sensor only in non-hazardous environments.

Remove the rain cap, metal sensor housing, and other components as described above for filter replacement. Grasp the grey sensor module and carefully pull out to remove the sensor. Insert a new sensor module, and reassemble in reverse order.

IMPORTANT! Always perform a full calibration after removing a sensor.

5.3 LCD or Circuit Board Replacement

The entire LCD/Circuit board assembly must be replaced as a unit as they cannot be separated, as follows:

1. Open the housing and remove the cover and circuit board/LCD assembly as described in Section 3 for wiring. Disconnect the wiring plugs.
2. Replace the Circuit Board/LCD assembly and re-assemble in reverse order.

Images show steps for replacing the LCD/Circuit board assembly, including opening the housing, removing the cover, and disconnecting wiring plugs.

6. Troubleshooting

For replacement parts please contact an authorized mPower Service Center.

6.1 4-20 mA Alarm Signals

To aid in troubleshooting, in addition to display text and LEDs, the 4-20 mA output identifies some alarms, as follows:

NOTE: If a Cal Failure has been corrected with a good calibration after the cause is corrected, everything should proceed normally. If parts are replaced while the transmitter is off, it should still be in Cal Failure until a good calibration is performed after restart. Exception: If the sensor is replaced and the calibration data are stored on the sensor microprocessor, then it will likely reboot with no fault. However, it will still be preferable to perform a good calibration for the local ambient atmosphere and conditions.

7. Technical Specifications

Diagrams show dimensions of the VOXI EC detector in mm and inches, including front, side, and overall views. A separate diagram illustrates electrical connections with terminal numbers.

All specifications are subject to change without notice. Please check for updates at www.mpowerinc.com .

8. Replacement Parts

* Prices subject to change. Check the latest Price Guide for current pricing.

Images display various replacement parts: Safety barrier, EC Sensor Module, Calibration Cap, Rain Cap, IR Programmer, Mounting bracket, EC Sensor Module, Gasket, Inlet Filter, Mesh Screen, Sensor Housing, and the main PC board with LCD display assembly. Another image highlights the VOXI enclosure and connector.

Technical Support and mPower Contacts

mPower Electronics Inc.

2910 Scott Blvd. Santa Clara, CA 95054

Phone: (408) 320-1266

Fax: (669) 342-7077

info@mpowerinc.com

www.mpowerinc.com