ACM DTM Series User manual

DTM Series
Digital Transmitter Module
Installation and Operating Instructions for the
AMC DTM Sensor Transmitter
IMPORTANT:
Please read these instructions completely and carefully
before installing and operating of this equipment.
filename: Manual_DTM_Transmitter.doc Original, 09 June 2004 Copyright ©, June 2004
The Armstrong Monitoring Corporation
215 Colonnade Road South, Nepean, Ontario, Canada K2E 7K3
Tel: [phone] • Fax: [phone] • U.S. Toll Free: [phone]
E-mail: [e-mail] • Internet: www.armstrongmonitoring.com

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TABLE OF CONTENTS
SECTION TITLE PAGE
1 Warranty........................................................................................................................iii
1.1 Liability........................................................................................................................... iii
1.2 Modifications and Substitutions...................................................................................... iii
1.3 Product Return............................................................................................................... iii
2 Product Information.....................................................................................................iv
2.1 Transmitter.....................................................................................................................iv
2.2 Factory Settings .............................................................................................................iv
3 Production Description.................................................................................................1
3.1 General Description.........................................................................................................1
4 Installation .....................................................................................................................2
4.1 Location and Mounting....................................................................................................2
4.2 Cable Selection...............................................................................................................3
4.3 Electrical Interfaces.........................................................................................................5
4.3.1 Input Power Supply .........................................................................................................5
4.3.2 Analogue Output (4-20 mA).............................................................................................5
4.3.3 MODBUS RS485 Interface..............................................................................................7
5 Operation.......................................................................................................................9
5.1 Operator Interface...........................................................................................................9
5.1.1 Touch Screen Keypad Operation.....................................................................................9
5.1.2 Liquid Crystal Display....................................................................................................10
5.2 Device Programming Menu...........................................................................................12
5.3 Features........................................................................................................................16
5.3.1 Keypad Inactivity...........................................................................................................16
5.3.2 Scroll Speedup..............................................................................................................16
5.3.3 Key Press Indication......................................................................................................16
5.3.4 Displaying Currently Configured Values........................................................................16
5.3.5 Fail Alarm Condition......................................................................................................16
5.3.6 Power Up Sequence......................................................................................................17
5.3.7 Manufacturing Data.......................................................................................................17
5.3.8 Modbus .........................................................................................................................17
5.3.9 Test...............................................................................................................................17
5.4 Gas Alarm Options........................................................................................................17
5.4.1 Threshold......................................................................................................................17
5.4.2 Type..............................................................................................................................18
5.4.3 Name ............................................................................................................................18
5.4.4 Activation Delay (On Delay)..........................................................................................18
5.4.5 Silence Timer ................................................................................................................19
5.4.6 Minimum Run Time (Run Time).....................................................................................19
5.5 Transmitter Options.......................................................................................................19
5.5.1 Gas label.......................................................................................................................19
5.5.2 Hysteresis .....................................................................................................................19
5.5.3 Zero Buffer....................................................................................................................20
5.5.4 Range............................................................................................................................20

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5.5.5 Engineering Units..........................................................................................................20
5.5.6 Pre-config (Predefined Configuration) ...........................................................................21
5.5.7 Sensor Configuration.....................................................................................................21
5.5.8 Password ......................................................................................................................21
5.5.9 Relays Option................................................................................................................22
6 Calibration Procedure.................................................................................................23
6.1 General .........................................................................................................................23
6.2 Calibration Procedure....................................................................................................24
6.2.1 Using Gas Depletion As A Measure Of Another Gas’s Concentration ...........................25
7 Preventive Maintenance..............................................................................................26
7.1 Maintenance..................................................................................................................26
7.2 Sensor Replacement and Wiring...................................................................................26
7.2.1 Sensor Interface............................................................................................................27
Appendix A - Modbus Accessible Data.................................................................................28

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1Warranty
AMC products are warranted against defects in material and workmanship for a period of two
(2) years from date of delivery. During the warranty period, we will repair or replace
components that prove to be defective in the opinion of The Armstrong Monitoring Corporation.
We are not liable for auxiliary interfaced equipment, nor consequential damage. This warranty
shall not apply to any product which has been modified in any way, which has been repaired by
any other party other than a qualified technician or authorized AMC representative, or when
such failure is due to misuse or conditions of use.
1.1 Liability
All AMC products must be installed and maintained according to instructions. Only qualified
technicians should install and maintain the equipment.
AMC shall have no liability arising from auxiliary interfaced equipment, for consequential
damage, or the installation and operation of this equipment. AMC shall have no liability for
labour or freight costs, or any other costs or charges in excess of the amount of the invoice for
the products.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, AND
SPECIFICALLY THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THE
DESCRIPTION ON THE FACE THEREOF.
1.2 Modifications and Substitutions
Due to an ongoing development program, AMC reserves the right to substitute components and
change specifications at any time without incurring any obligations.
1.3 Product Return
All products returned for warranty service will be by prepaid freight and they will only be
accepted with an R.M.A. number issued by AMC. All products returned to the client will be
freight collect.
WARNING
USING ELECTRICALLY OPERATED EQUIPMENT NEAR GASOLINE, OR GASOLINE
VAPOURS MAY RESULT IN FIRE OR EXPLOSION, CAUSING PERSONAL INJURY AND
PROPERTY DAMAGE. CHECK TO ENSURE THE WORKING AREA IS FREE FROM SUCH
HAZARDS DURING INSTALLATION OR WHEN PERFORMING MAINTENANCE, AND USE
PROPER PRECAUTIONS.

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2Product Information
2.1 Transmitter
Sensor/ Transmitter Unit Order Number
Transmitter Part Number
Transmitter Serial Number
Sensor Part Number
Sensor Serial Number
Power Supply Requirements 12 to 24 Vdc @ 70 mA
2.2 Factory Settings
Gas Type
Range
Zero Gas, at 4 mA signal
Gas Concentration at 20 mA signal

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3Production Description
3.1 General Description
The AMC-DTM series sensor/transmitter micro-controller based unit is designed to provide
continuous, reliable surveillance of surrounding air for traces of a specific hazardous gas. There
is a broad range of electrochemical gas sensors available for use with the DTM Transmitter.
Parameters for each type of sensor are stored in memory allowing the operator to easily change
gas types when installing different sensors. The DTM provides a non-intrusive operator
interface allowing calibration and configuration. This allows the operator to calibrate and
change settings while maintaining the explosion proof integrity of the transmitter. These
changes are made using a touchscreen keypad that is accessible through the glass window of
the enclosure using your finger. The DTM provides several different outputs for
interconnectivity. There is a 4 to 20 mA, variable current signal that is proportional to the gas
concentration detected, Modbus RTU/ASCCI 2 wire interface on the standard unit and an
optional relay card with contacts for three alarm thresholds and fail. Each sensor/transmitter
unit is factory calibrated and is ready for field installation and operation.

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4Installation
4.1 Location and Mounting
The sensor/transmitter should be mounted in a location sufficient enough for the sensor to
receive its environment, and secure from potential mechanical damage. It should remain clean
and free from debris. The internal area of the transmitter enclosure must be kept clean and dry.
Mount the sensor/transmitter in a location such that it will not experience submersion in liquids,
exposure to extreme temperatures, and electrical noise signals.
The sensor housing SHOULD NOT touch the mounting surface. In some cases, it may require
the use of a spacer between the mounting surface and the transmitter housing as per Figure
4-1.
Note: Mounting arrangement of transmitter housing depends on location of transmitter, and
mounting surface. Mounting hardware NOT supplied.
Figure 4-1: Mounting of transmitter housing

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4.2 Cable Selection
Connection should be made using 3-conductor shielded cable. For best signal transmission and
maximum noise rejection, run cable through steel conduit (cable shield must be grounded at the
monitor or power supply). For basic cable selection (between monitor and transmitter) when
using a 250 ohm load resistance, use the following chart:
Cable Selection Chart
Wire Gauge Cable Length
Feet Metres
AWG @ 12 Vdc @ 24 Vdc @ 12 Vdc @ 24 Vdc
22 1000 15000 305 4732
20 1500 23000 457 7010
18 2500 38000 762 11582
16 3800 57000 1158 17373
For applications not covered by the above chart, an example is shown below for selecting the
right cable, using the graph in Figure 4-2 and the following formulas. Please note that some
non-AMC equipment may have the load resistance built-in.
EXAMPLE: (Refer to Figure 4-2)
Known data: Obtained from measurements, ratings or specifications.
Power supply 17 VDC
Load resistance 180 Ohms
Wire gauge 20 AWG
Cable length / 1 Ohm resistance 43.6ft (13.3m) typical
Calculations on the graph: Using the power supply voltage as reference.
Maximum resistance MR
Load resistance LR
Formula 1: To determine remaining safe loop resistance.
Maximum resistance 518 Ohms
Load resistance –180 Ohms
Remaining resistance = 338 Ohms
Formula 2: To determine maximum safe cable length allowed.
Remaining resistance 338 Ohms
Cable length (for 1 Ohm) x 43.6 Feet
Maximum safe cable length = 14736 Feet

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Figure 4-2: Cable Selection Graph

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4.3 Electrical Interfaces
4.3.1 Input Power Supply
The AMC-DTM series sensor/transmitter requires an input power supply as follows.
Value
Parameter Min Max Units
Input Voltage (VIN) 12 24 VDC
Power Consumption 5.0 2.5 W
Table 4-1: Input Power Supply
4.3.2 Analogue Output (4-20 mA)
For installation to a DC Power Supply only, the AMC-DTM series sensor/transmitter is field
wired as illustrated in Figure 4-3. The terminal block pinout for TB-3 is given in Table 4-2 and
output specifications are provided in Table 4-3.
Figure 4-3: Typical Field Wiring of AMC-DTM to DC Power Supply

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For installation to an AMC Monitor, the AMC-DTM series sensor/transmitter is field wired as
illustrated in Figure 4-4. The terminal block pinout for TB-3 is given in Table 4-2 and output
specifications are provided in Table 4-3.
Figure 4-4: Typical Field Wiring of AMC-DTM to AMC Monitor
Terminal Type Description
1 PWR Input Voltage (+)
2 PWR Input Voltage (+)
3 ANALOG OUT 4-20mA Output Signal (S)
4 PWR Power Supply Common (-)
5 PWR Power Supply Common (-)
Table 4-2: TB3 Interface Pinout
Value
Parameter Min Typ Max Units
Load Resistance n/a 250 275 ohms
Loop Current 0.25 21 mA
Conductor Size See Note 16 AWG
Table 4-3: 4-20mA Output Specifications

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4.3.3 MODBUS RS485 Interface
For installation in a MODBUS configuration, the AMC-DTM series sensor/transmitters are field
wired as illustrated in Figure 4-5. The terminal block pinout for TB-2 is given in Table 4-4 and
RS485 specifications are provided in Table 4-5 and Table 4-6.
Figure 4-5: Typical Field Wiring of Multidrop MODBUS Installation
Terminal Type Description
1 IN/OUT RS485 Transmit/Receive
Data A (T/RXA)
2 IN/OUT RS485 Transmit/Receive
Data B (T/RXB)
Table 4-4: TB2 Interface Pinout
Value
Parameter Min Typ Max Units
data rate 1200 19200 57600 bps
Parity NONE/EVEN/ODD
Data Bits (LSB sent first) 8 Bits
Stop Bits 1 Bits
Start Bits 1 Bits
Voltage 5 24 VDC
Conductor Size 26 16 AWG
Table 4-5: RS485 Interface Specification (RTU Modbus Mode)

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Value
Parameter Min Typ Max Units
data rate 1200 19200 57600 bps
Parity NONE/EVEN/ODD
Data Bits (LSB sent first) 7 Bits
Stop Bits 1 Bits
Start Bits 1 Bits
Voltage 5 24 VDC
Conductor Size 26 16 AWG
Table 4-6: RS485 Interface Specification (ASCII Modbus Mode)

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5Operation
The transmitter has a non-intrusive operation interface. The front face contains a capacitive
contact that operates like normal push buttons. To operate a push button, simply place your
index finger on the glass over the desired arrow.
5.1 Operator Interface
Operator Interface, illustrated in Figure 5-1, consists of a four-button keypad, four LEDs and a
LCD. The DTM provides a non-intrusive operator interface allowing calibration and
configuration. This allows the operator to calibrate and change settings while maintaining the
explosion proof integrity of the transmitter. LED’s A1, A2 and A3 denote active alarms when
illuminated in the color red. LED F denotes unit failure when illuminated in the color amber.
Figure 5-1: Transmitter Operator Interface
5.1.1 Touch Screen Keypad Operation
The touch screen keypad consists of four targets, as illustrated in Figure 5-2, that are activated
by either touching the sensor pad itself, or touching the viewing window of the transmitter
housing.
•Button “Back” cancels current operation and goes back in the menu hierarchy. It also
serves as “no” choice, when offered. When entering text or numbers, it returns entry
point back one character.
•Buttons “Up” and “Down” scroll submenu items. They can also scroll numeric or
alphanumeric characters, depending on the context.

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•Button “Forward” enters currently scrolled submenu. It also serves as “yes” choice,
when offered. When entering text or numbers, it moves entry point forward one
character.
Figure 5-2: Keypad part of the Operator Interface
5.1.2 Liquid Crystal Display
Liquid Crystal Display (LCD) displays 12 characters in each of the two lines (2x12). The color
of the characters is yellow on dark blue background.
During normal operation, the transmitter shows the gas label in the first LCD line and the current
gas concentration in the second line expressed in the chosen Engineering Units. See Figure
5-3. Engineering Units, section 5.5.5, describes different formats of the gas concentration value
applicable to Figure 5-3.
Cl2
999.9%LEL
FA1A2A3
Figure 5-3: Gas Concentration Display

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When an Alarm is declared, LCD displays Concentration Display and Alarm Display in 2 two-
second flash periods. See Figure 5-3 and Figure 5-4.
ALARM 1
> 50.0%LEL
FA1A2A3
Figure 5-4: Alarm Display
The first line shows the name of the active alarm. The second line shows the condition
triggering the alarm. “>” character is used for increasing alarms and the “<” for decreasing. The
concentration value (50.0%LEL in the example) is the value of the alarm threshold. Alarm LED
rapidly flashes when the corresponding alarm is active.
It is possible to change default alarm names (ALARM 1, ALARM 2 and ALARM 3) to an
operator defined value. See Figure 5-5.
fan is on
> 10.0%LEL
FA1A2A3
Figure 5-5: Alarm display – renamed alarm
Active alarms are displayed in flash cycles together with the Default Display. Up to four displays
can be shown this way (three gas alarms and the default display). Gas alarms are mutually
exclusive. They can be active in any order or combination.
During the Minimum Run Time period, hourglass symbol is displayed in the second line. See
Figure 5-6. Alarm LED flashes slowly when the alarm is in this mode.
ALARM 1
> 50.0%LEL
FA1A2A3
Figure 5-6: Alarm display during Minimum Run Time
When alarm is silenced, the character “s” is also displayed together with the hourglass symbol
during the silence period. See Figure 5-7. Alarm LED flashes slowly when the alarm is in this
mode.

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ALARM 2
> 80.0%LEL s
FA1A2A3
Figure 5-7: LCD - Alarm display during Silence period
When the transmitter detects a failure, Fail Alarm condition is displayed. See Figure 5-8.
FAIL
LCD
err 140:l
FA1A2A3
Figure 5-8: FAIL Alarm display
5.2 Device Programming Menu
The following is a graphical representation of the programming menu of the transmitter
provided for assisting the operator in configuring the transmitter parameter.
Silence_____
all_________
alarm 1_____
alarm 2_____
alarm 3_____
log in______
0___________
calibrate___
Zero________
stable?
Span________
0000.0ppm___
------------
stable?

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options_____
alarm 1_____
threshold___
0000.0ppm___
type________
disabled____
increasing__
decreasing__
On Delay____
00min_______
Silence_____
00min_______
Run Time____
set value___
00min______
infinite____
name________
ALARM 1_____
alarm 2_____
alarm 3_____
Range_______
0000.0ppm___
Hysteresis__
0.0%Range___
Zero Buffer_
0.0%Range___
gas label___
name________
relays______
alarm 1 __
norm.eng____

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norm.de-eng_
alarm 2
alarm 3
Fail___
test________
are you sure?
advanced____
password____
enter old:__
0___________
------------
enter new:__
0___________
------------
new again:__
0___________
Modbus______
address_____
001_________
type________
ASCII_______
RTU_________
data rate____
1200bps_____
2400bps_____
4800bps_____
9600bps_____
19200bps____
38400bps____
57600bps____
sensor______