GDS GASMAX ECx Manual

Operation & Maintenance Manual
GASMAX ECx
Toxic / Oxygen Battery-Powered Gas Monitor with
Smart Sensor Interface
Important: Read and understand contents of this instruction manual
prior to use. Improper use of equipment could result in
instrument malfunction or serious injury.
GDS Corp.
2513 Hwy 646
Santa Fe, Texas 77510
[phone]
[phone] (FAX)
www.gdscorp.com
[email protected]

GASMAX ECx Instruction Manual Revision 1.1
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Table of Contents
SECTION 1 – SAFETY INFORMATION......................................................................................... 3
1.1 Safety Information – Read Before Installation & Applying Power ......................... 3
1.2 Contacting GDS Corp.................................................................................................. 3
SECTION 2 – GENERAL DESCRIPTION ...................................................................................... 4
2.1 Introduction.................................................................................................................. 4
2.2 Description of the Wireless System.......................................................................... 5
2.2.1 RF900 Radio Status (RS) Icons........................................................................... 5
2.2.2 “Radio Awake” Control Timing and Conserving Battery Life......................... 6
2.2.3 GM ECx BATTERY # 10-0293.............................................................................. 6
2.2.4 GM ECx 900MHZ RF MODULE # 10-0291........................................................... 7
SECTION 3 – INSTALLATION INSTRUCTIONS........................................................................... 8
3.1 Ratings and Certifications.......................................................................................... 8
3.2 Sensor Location .......................................................................................................... 8
3.3 Mounting the Enclosure.............................................................................................. 8
3.3.1 10-0322 Magnetic Mount Option......................................................................... 9
3.4 System Design Specifications ................................................................................. 10
3.5 Antenna Transmission Range.................................................................................. 10
3.5.1 Antenna Selection.............................................................................................. 11
3.6 Sensor Installation (with Smart / Simple Sensor Definition)................................. 11
3.7.1 “Sensor Type” and GM ECX Signal Conditioning.......................................... 13
SECTION 4 – INITIAL START-UP................................................................................................ 13
4.1 “Transmitter Configuration” Menu.......................................................................... 13
4.2 Initial Toxic / Oxygen Monitor Start-Up................................................................... 13
4.2.1 Initial Toxic / Oxygen Monitor “Span” Check.................................................. 14
SECTION 5 – OPERATING INSTRUCTIONS.............................................................................. 14
5.1 CAL MODE - Routine Sensor Calibrations.............................................................. 14
5.2 ALARM OPERATION................................................................................................. 16
5.2.1 ALARM 3 – UNDERSTANDING FAULT / LEVEL OPERATION ....................... 16
SECTION 6 – SETUP MENU CONFIGURATION ........................................................................ 17
6.1 Menus Database Configuration ............................................................................... 17
6.2 Configuration Using the Magnetic Wand:............................................................... 17
6.3 System Configuration Menus: ................................................................................. 18
6.4 Alarm Settings:.......................................................................................................... 19
6.5 Sensor Information: .................................................................................................. 20
6.6 Clock / Warm-Up & Cal Purge Delays SETUP: ....................................................... 20
6.7 COMMUNICATIONS SETUP: .................................................................................... 21
6.7.1 GM ECx AND C1 BASE STATIONS: ................................................................. 22
6.8 SYSTEM SECURITY: ................................................................................................. 22
6.9 LCD Contrast Adjustment: ....................................................................................... 23
SECTION 7 – TECHNICIANS ONLY MENUS.............................................................................. 23
7.1 Introduction: .............................................................................................................. 23
7.2 Set Gain to Unity (Technicians only!): .................................................................... 24
7.3 PreAmp Gain Adjust (Technicians only!): .............................................................. 24
7.4 Simple Sensor Input Type (Technicians only!):..................................................... 24
7.5 Zero Cal Value (Technicians only!): ........................................................................ 25
7.6 Raw Min / Max Counts (Technicians only!): ........................................................... 25

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SECTION 1 – SAFETY INFORMATION
1.1 Safety Information – Read Before Installation & Applying Power
IMPORTANT
Users should have a detailed understanding of GM ECx operating and maintenance instructions.
Use the GM ECx only as specified in this manual or detection of gases and the resulting
protection provided may be impaired. Read the following WARNINGS prior to use.
WARNINGS
•Calibrate with known target gas at start-up and check on a regular schedule, at least
every 90 days. More frequent inspections are encouraged to spot problems such as dirt,
oil, paint, grease or other foreign materials on the sensor head.
•Do not paint the sensor assembly or transmitter.
•Do not use the GM ECx if its enclosure is damaged or cracked or has missing
components.
•Make sure the cover, internal PCB’s and field wiring are securely in place before
operation.
•Use only a sensor assembly compatible with the GM ECx.
•Periodically test for correct operation of the system’s alarm events by exposing the
monitor to a targeted gas concentration above the High Alarm setpoint.
•Do not expose the GM ECx to electrical shock or continuous severe mechanical shock.
•Protect the GM ECx from dripping liquids and high power sprays.
•Use only for applications described within this manual.
CAUTION: FOR SAFETY REASONS THIS EQUIPMENT MUST BE OPERATED AND
SERVICED BY QUALIFIED PERSONNEL ONLY. READ AND UNDERSTAND INSTRUCTION
MANUAL COMPLETELY BEFORE OPERATING OR SERVICING.
ATTENTION: POUR DES RAISONS DE SÉCURITÉ, CET ÉQUIPEMENT DOIT ÊTRE UTILISÉ,
ENTRETENU ET RÉPARÉ UNIQUEMENT PAR UN PERSONNEL QUALIFIÉ. ÉTUDIER LE
MANUE D’INSTRUCTIONS EN ENTIER AVANT D’UTILISER, D’ENTRETENIR OU DE
RÉPARER L’ÉQUIPEMENT.
1.2 Contacting GDS Corp.
GDS Corp technical support is available between the hours of 7:30am and 5:00pm Monday
through Thursday and 7:30am until Noon on Friday Central Standard Time. Please call 409-927-
2980 or FAX [phone]. Our email address is inf[email protected] and our website is
www.gdscorp.com. Our shipping address is 2513 Hwy 646, Santa Fe, TX 77510.

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SECTION 2 – GENERAL DESCRIPTION
2.1 Introduction
IMPORTANT: This manual describes only GM ECx toxic / oxygen gas monitor equipped with
internal RF wireless modem and RF900 firmware. This battery powered device has no external
power or signal wiring and is limited to self powered electrochemical sensors for toxic and oxygen
measurements. A separate manual is available for the GASMAX IIx, an externally powered
wireless monitor for bridge-type sensors. Both are single channel fixed-point monitors designed to
provide continuous monitoring of hazardous gases in the workplace. Gas values are graphically
displayed in engineering units in either bar-graph or 30-minute trend formats (Figure 2-1).
Flashing front panel LED’s help notify personnel when alarm levels have been reached. Only
periodic calibration checks are needed to assure dependable performance.
The GM ECx provides a license free 900MHZ wireless link to any GDS Corp C1 Protector
Controller or C2 Quad Protector controller (when configured with an RF900 wireless modem). Up
to 16 GM ECX wireless monitors may communicate to one C1 Controller.
Advanced microcontroller electronics and superior graphic LCD operator interface offers
enhanced diagnostics and fault analysis not possible in competing products. Non-volatile
memory retains all configuration data during power interruptions. The magnetic keypad allows
non-intrusive calibrations to be easily performed by one person without opening the enclosure. A
standard “real time clock & calendar” feature allows event logging of calibrations and alarm trips
for review on the LCD readout.
Compatible sensors include an 8-wire Smart Sensor interface capable of configuration data
uploads to the monitor as well as traditional Simple sensors with three-wire interface. A separate
PC compatible USB Interface device (part # 10-0252) allows Smart sensors to be preloaded with
configuration variables via a PC; when connected, the GM ECx gives the user the option to
upload this data to the GM ECx. This configuration data includes alarm set points, range, target
gas, calibration constants and other variables required to match the GM ECX to a specific
application. For Simple sensors with no smart interface, the USB device allows direct GM ECx
configuration from a PC or a six channel GM ECX Educator device.
Additional features include:
•On screen radio status icons indicate “Server In Range”, “Server Out of Range” and “Low
Battery” conditions.
•No potentiometer or jumper settings required. All setup is done with menus accessed via the
LCD / magnetic keypad operator interface without opening the enclosure.
•Field adjustable alarm levels flash front panel LED indicators for HIGH, WARN, FAIL
conditions. Relays are not available with this low power model.
•CAL MODE advises when to apply gas during calibrations.
•A thirty-minute trend screen shows rate of change of gas exposures.
•Sensor life bar-graph updates after each SPAN calibration.
•Modular design affords efficient installation and plug in sensors allow changing target gases
after installation.
•New smart sensors are recognized by the GM ECx and prompts users to either upload new
configuration data or continue with data from the previous smart sensor.
•Sensors are industry proven for fast response and long life.

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Figure 2-1: Data Displays
2.2 Description of the Wireless System
All GDS Corp wireless transceivers utilize a FHSS (Frequency Hopping Spread Spectrum)
Server-Client network where multiple Clients synchronize their frequency hopping to a single
Server. The Server transmits a beacon at the beginning of every frequency hop (50 times per
second). Client transceivers listen for this beacon and upon receiving it synchronize their
hopping with the Server.
Each GM ECx wireless “broadcast” includes a 10-bit monitored gas value, battery voltage
indication and a status byte. When equipped with optional radio modems, C1 Protector and C2
Quad Protector Controllers are capable of functioning as Clients or Servers. Multiple GDS Corp
controllers may receive transmissions from the same GM ECx gas monitor, but only one
controller per wireless network may be configured as the Server.
Each transceiver on a wireless network must have its RADIO SETUP menus configured to share
the same Hop Channel (0-32) and System ID (0-255) to communicate (see section 6.7). There
should never be two servers with the same Hop Channel / System ID settings in the same
coverage area. The Server must be in a powered location and should be centrally located since
all Clients must receive the server’s beacon in order to communicate.
Correct planning and design of wireless systems are imperative for ensuring a successful
installation. It is highly recommended that a site drawing indicating location of monitors and base
station, line of site obstructions, and sources of RF interference be submitted when requesting a
quotation.
2.2.1 RF900 Radio Status (RS) Icons
Figure 2-1 shows the GM ECx data display and identifies the “radio status” (RS) icon which
appears on the LCD screen upper left corner. Status conditions indicated by the RS icon are
Zzz’s (sleep mode), Server In Range (server beacon received), Server Out of Range (server
beacon not received) and Low Battery. Low Battery conditions also flash the FAIL led.
It is important to understand RS icons only update as the TXD LED flashes indicating an RF
transmission has occurred. RF transmissions typically occur on 5-minute intervals, but increase
to six-second intervals during alarm conditions.

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2.2.2 “Radio Awake” Control Timing and Conserving Battery Life
Most GM ECx battery power is consumed as the radio communicates to the wireless network.
Each communications cycle consists of the following sequence: Wake the radio in receive mode;
listen for the Server’s beacon; synchronize to the Server’s hopping frequency; transmit data
packet, return to sleep mode. This sequence takes between 0.25 to 1 second to complete.
Transmit power levels are adjustable; lower power setting will result i longer the battery life.
Every six seconds, the monitor performs a “sniff test” to detect level of target gas present at the
sensor. At each “sniff test”, the Zzz’s RS icon is briefly replaced by “Server In Range” or “Server
Out of Range” icon and the readout is updated to indicate the current gas value. The radio
remains in sleep mode if the gas value does not trip either the A1 or A2 alarm. Upon each 50th
consecutive “sniff test” (every 5-minutes) the radio wakes up, receives the Server’s beacon, and
transmits the latest gas data. These 5-minute transmissions ensure that all controllers can
monitor the wireless communications link even when no alarms exist. If A1 or A2 alarms do exist
during the “sniff test”, the radio wakes, receives the Server’s beacon, and transmits its data
immediately.
The following list identifies each of the conditions that cause the radio to transmit:
•Five minutes, or fifty sequential reads (when there is no A1 or A2 alarm). Any receiving
controller will report a “Communications Error” if the GM ECx does not reply for periods of
greater than 18-minutes. A3 and FAIL alarms do not increase radio transmission rates.
•Every six seconds, if there is an A1 or A2 level alarm.
•Upon entry into CAL mode a value of 75 (-15.6% scale) is transmitted. Controllers so
programmed will indicate “IN CAL” when this occurs.
•Upon entry into CAL PURGE mode a value of 200 (0% scale) is transmitted.
NOTE: Oxygen sensors transmit a value of 20.9% upon entry into CAL PURGE mode.
•Holding the magnet over the UP key for >10seconds forces a transmission of the current
reading value.
2.2.3 GM ECx BATTERY # 10-0293
GM ECx electronics consists of the lower 10-0299/Battery I/O PCB (Figure 2-2) connected by a
cable to the upper Display assembly with 10-0291 RF Module PCB (Figure 2-3). The 10-0293
3.6 volt lithium ‘D’ cell battery will continuously power the unit for up to one year and may be
replaced by following the procedure in Figure 2-2.
Power switch (SW1), on the 10-0299 Battery PCB, applies battery power to the GM ECx monitor.
SW1 should be OFF if the monitor is to be out of service for long periods.
IMPORTANT: Do not turn SW1 ON until the controller designated as Server is fully operational
and ready to communicate to the GM ECx. Battery life is reduced if the GM ECx is on for long
periods while unable to communicate to the Server controller.
IMPORTANT: DO NOT ATTEMPT TO CHARGE THIS BATTERY OR REPLACE WITH ANY
OTHER THAN PART #10-0293 FROM GDS CORP.

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Figure 2-2: 10-0299/Battery I/O PCB
2.2.4 GM ECx 900MHZ RF MODULE # 10-0291
The 10-0291 RF module mounts “piggy back” to the back of the Display assembly as shown in
Figure 2-3. The MMCX RF connector connects to the antenna fitting’s pigtail coax cable. There
is also a slender 4 conductor cable between the 10-0291 and the 10-0299 battery I/O PCB bolted
to the bottom of the enclosure.

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SECTION 3 – INSTALLATION INSTRUCTIONS
3.1 Ratings and Certifications
The enclosure is NRTL certified for Division 1 hazardous area installations for explosion-proof
Class 1 Groups B,C,D (see Figure 3-1). The GM ECx is designed to meet ISA 92.0.01 Part 1 for
Toxic Monitors. The 10-0295 antenna fitting has an RP-SMA connector and is suitable for
Division 2 classified areas. An optional 1000-2193 antenna is also available for Division 1
classified areas. Figure 3-3 shows both antenna styles.
3.2 Sensor Location
Factors such as air movement, gas density in relation to air, emission sources and environmental
variables affect correct sensor location. Air movement by fans, prevailing winds and convection
should be carefully evaluated to determine if a leak is more likely to raise gas levels in certain
areas within the facility. Vapor density of a gas determines if it will rise or fall in air when there
are no significant currents. Lighter than air gases should have the monitors mounted 12 – 18
inches (30 – 45 centimeters) above the potential gas leak and heavier than air gases should be
this distance below. Even though the GM ECx is designed for rugged service, sensors should be
protected from environmental damage from water, snow, shock, vibration and dirt.
3.3 Mounting the Enclosure
The GM ECx standard enclosure is a cast aluminum explosion-proof (NEMA 7) enclosure. The
GM ECx antenna should typically be mounted with “line of sight” access to the controller’s base
station antenna. If a good “line of sight” angle is not possible the GM ECx will usually still function
properly at ranges up to 1500 feet but obstructions should be kept to a minimum.
WARNING: Qualified personnel should perform the installation according to applicable electrical
codes, regulations and safety standards. Ensure correct cabling and sealing fitting practices are
implemented. Install the GM ECx to a wall or bracket using the predrilled mounting flanges with
I.D. 0.25 on 5.0 inch centers (Figure 3-1).
CAUTION: The sensor head should never be installed pointing upwards.

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Figure 3-1: GM ECx Explosion-Proof Housing
Modular design simplifies the installation of the GM ECx (Figure 3-2). A top Display Assembly is
mounted with captive thumbscrews and is easily removed to access internal components. The
RF900 module mounts piggyback to the back of the Display Assembly. Wiring from toxic or
oxygen sensors terminates at the10-0232 Display Assembly. This Display Assembly is the only
PC board supplied with the toxic / oxygen GM ECx. The enclosure is equipped with two threaded
3/4 inch NPT conduit fitting outlet and pre-drilled mounting flanges.
WARNING: Qualified personnel should perform the installation according to applicable electrical
codes, regulations and safety standards. Insure correct cabling and sealing fitting practices are
implemented. Do not aim the sensor pointing upward. Install the GM ECx to a wall or bracket
using the predrilled mounting flanges with I.D. 0.25 on 5.5 inch centers (Figure 3-1). If conduit is
rigid and able to support the weight of the GM ECX, the mounting bolts may be omitted.
CAUTION: The sensor should never be installed pointing upwards.
3.3.1 10-0322 Magnetic Mount Option
GDS Corp offers a magnetic mount for the GM ECx instrument enclosure. The 10-0322Magnetic
Mount securely attaches the assembly to any solid steel structures that is at least 6 inches wide.
Figure 3-2: Outline Drawing

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3.4 System Design Specifications
Power Supply: Integral non-rechargeable 3.6 volt 19AH lithium D cell battery. Replacement part
# 10-0293.
Power Consumption: <2mA during “sleep” mode, 40mA during “receive beacon” mode, up to 1
amp during 1 watt “transmit” mode. Transmit power may be set from 10mW to 1 watt (see
Section 6-7)
Transmit (TX) Power: 30dBm at highest 1W power setting. Transmit power may be set from
10mW to 1 watt (see Section 6-7)
Receive (RX) Sensitivity: -100 dBm
Radio Frequency: Hopping occurs between 902 – 928MHZ.
Memory: Non-volatile E2memory retains configuration values in the event of power outages.
3.5 Antenna Transmission Range
The distance radio signals can travel is dependent upon several factors including antenna design,
transmitter power and free space losses. In order for a wireless link to work, the available system
operating margin (TX power - RX Sensitivity + Antenna gains) must exceed the free space loss
and all other losses in the system. For best RF line-of-site, the combined height of both antennas
must exceed the Fresnel zone diameter (see below).
Dist. between ant's Fresnel zone diameter Freespace loss (dB)
1000 ft (300 m) 16 ft (4.9 m) 81
1 Mile (1.6 km) 32 ft (9.7 m) 96
5 miles (8 km) 68 ft (20.7 m) 110
10 miles (16 km) 95 ft (29 m) 116
Example:
The RF900 radio modem has the following parameters:
•Maximum RF900 TX power setting = 30 dBm (1 Watt)
•RF900 RX sensitivity = -100 dBm (this is a constant)
•Antenna gain (standard equipped dipole) = 2.1dBi x 2 = 4.2dBi
So the system operating margin at ten miles is 30 + 2.1 -116 + 2.1 + 100 = 18.2 dBm. This
margin should be enough to transmit 10 miles if free space was the only loss in the system. For
this to be the case, however, the antennas must be mounted with a combined height greater than
95ft above all obstructions. In practice however, there are many losses in the system besides just
free space and it is recommended there be at least 20dB to 40dB system operating margin.
RF “Rules of Thumb”
•Doubling the range with good RF “Line of Sight” (LOS) increases the free space loss by
at least 6 dB.
•Doubling the range without good RF LOS increases the free space loss by at least 12 dB.