In a world that is becoming increasingly technology driven and interconnected, the timely
recovery of consumption data from remote locations is now more critical than in the past.
The cellular IMU-II/s is positioned to address this requirement by combining the proven
IMU-II/s data collector with the latest GSM cellular phone technology.
Highlights of the Cellular IMU-II/s product are listed below:
• Two pulse input channels are provided for accumulation of time-tagged data with a
maximum pulse rate of 10 Hertz.
• Alarm inputs trigger an immediate call to the central computer, thereby notifying
personnel at the central computer site of any fault conditions.
• Power options include AC power with lead-acid backup or a fully battery powered
device. (This manual discusses the battery powered configuration only.)
• Wireless communications are via a Siemens GSM cellular phone. This cellular format
replaces the older analog system that is now being phased out of service.
Figure 1-1 provides an illustration of the complete product installation from end-to-end.
Cellular System Site.
IMU-II/S (GSM) HARDWARE
Figure 1-2 illustrates the major components of the cellular IMU-II/s that the user should
become familiar with:
Cellular IMU-II/s (GSM)
Theory of Operation
Each component used in the construction of the Cellular IMU-II/s serves a specific
purpose as detailed below:
• Lantern Battery:
Provides electrical power to the battery charger board, which in turn maintains a
charge on the lead acid battery. A boost power supply circuit on the battery
charger board converts the lantern battery voltage of 6 volts to a nominal 13.0
volts that is used to charge the lead acid.
• Lead Acid Battery:
This battery supplies the energy to the cellular phone when a call is being placed.
A lead acid battery is necessary for providing the peak currents required by the
radio and to support the long duration calls that sometimes take place. The lead
acid battery can be thought of as a reservoir of energy that is maintained at full
charge by the lantern batteries.
• Lithium Battery:
Power for the data collection board is provided by the ‘D’ size 3.6 volt lithium
battery pack. This power source is independent of the other batteries and typically
does not need to be replaced as often as the lantern cells. A low battery detection
circuit contained within the IMU-II/s provides an alarm when it has reached a low
• Battery Charger Board:
Contains a boost power supply circuit that converts the 6V levels provided by the
lantern cells to a 13.0V charging voltage to maintain the lead acid battery. A low
battery detect circuit monitors the voltage on the lantern cells and triggers an
alarm on the IMU-II/s if the voltage becomes too low. In addition, the control
signal “VSW” from the IMU-II/s board determines whether the on-board
transistor switch should be activated to drive 12 volts from the lead acid battery to
the cellular radio. The wiring diagram found in Appendix-C provides additional
insight into the electrical connections between the various components.
• Siemens GSM Radio:
This compact GSM cellular radio is well suited to remote site data transmission
applications. A SIM card reader slot is located on the bottom side of the radio
housing and can be extracted by pressing the small circular button on the
immediate left-hand side with a pen tip or paperclip. The antenna connection
requires an external GSM antenna with sufficient cable length to feed into the
gland on the bottom of the enclosure and to attach to the FME type connector.
• IMU-II/s Board:
At the heart of the system is the IMU-II/s data collection board that contains an
intelligent microprocessor and operating program to perform a multitude of tasks.
At the most basic level, the IMU-II/s samples the pulse and alarm inputs at the
terminal block and will make a call based on either a programmed schedule or an
alarm event. Accumulated data information is transmitted over a serial data link to
the GSM radio, which in turn sends the data over the cellular network to the
central computer site.
• Tamper Switch:
Provides an alarm trigger (which initiates a call) when the enclosure door has
been opened for service.
Sequence of events during normal data collection mode:
a) Lantern batteries feed power to the battery charger board, which in turn
provides a light charging current to the lead acid battery.
b) The GSM radio is shutdown and has no power applied.
c) The data collection board (IMU-II/s) is sampling the pulse inputs and storing
data into RAM memory at a rate that is determined by the interval size. In
addition, the alarm inputs are being sampled to determine if an alarm event
Sequence of events when a call is being placed:
a) Lantern batteries continuously provide energy to the battery charger board,
which in turn provides a light charging current to the lead acid battery.
b) The IMU-II/s data collector determines that it is time to place a call due to
either an alarm event or a regularly scheduled call time.
c) VSW from the IMU-II/s is driven to a logic high, and is used to turn on the
power transistor switch of the battery charger board. This in turn causes +12V
from the lead acid battery to be applied to the GSM cellular radio.
d) The GSM radio turns on its receiver, verifies that the SIM card is valid and
registers with the network cellular tower. After validation, the LED on the
housing of the GSM radio lights solid green.
e) A call is placed by the IMU-II/s using the GSM radio to contact the
customer’s central computer site. After handshaking with the central computer
site MODEM, a connection is established at the 2400bps data rate.
f) Consumption data is sent over the cellular phone link to the central computer
site in ‘packets’. Each data ‘packet’ is checked for transmission errors before
g) At the end of the call session, the GSM radio is turned off (via the VSW
control signal), and the IMU-II/s returns to the normal data collection mode.
Figure 1-3 highlights the IMU-II/s board level components that are referenced
throughout the manual.
IMU-II/s Circuit Board
IMU-II/s Board Components
J2 Auxiliary port; provides the connection point for the RS-232 interface
board. Serial data is driven from this port to the GSM cellular radio.
J3, J4 Power connector terminals; power is provided to the IMU-II/s board via a
lithium battery pack.
J8 Programmer access port; this is used in conjunction with the Metretek
programmer software and cable to permit configuration memory updates
to the IMU-II/s.
J9 VSW power connector; provides an indication to the battery charger board
that the IMU-II/s is ready to place a call and that power should be applied
to the GSM radio.
TB1 Thirteen position terminal block; provides attachment point for the data
and alarm inputs.
U8 EPROM memory chip; contains the operating program for the IMU-II/s
Board (under shield plate). Due to periodic program updates containing
corrections and feature enhancements, it may become necessary to replace
this chip as new versions become available. When installing a new chip,
always ensure that the 'U' shaped detent faces towards the bottom of the
LED's Light Emitting Diodes; these serve to indicate communications status.
These lights will illuminate for a period of 4 minutes after initial
application of power, as well as during active communications.
Program Monitor Blinks to indicate that the microprocessor is
Call In Progress Illuminates when the IMU-II/s is initiating a call or
in active communications mode.
Carrier Detect Indicates that the GSM radio is connected to the
remote MODEM at the central computer site.
Receive Data / Good Call Blinks when data has been received from the central
computer, and will also light solid at the end of a
Transmit Data / Good Call Blinks as data is being transmitted out to the central
computer, and will light solid at the end of a good
RS-232 Interface Board
Position J2 of the IMU-II/s board is intended for mounting the small interface board
illustrated in Figure 1-4. This board provides the driver circuits to support the RS-232
signal levels required by the GSM radio. All connections to the interface board are
factory wired and do not require further consideration by the end user.
RS-232 Interface Board
Battery Charger Board
Figure 1-5 illustrates the basic layout of the battery charger board. The momentary
action toggle switch provides the Service Technician with a means to apply power
directly to the GSM radio for diagnostic purposes. If it should become necessary to
replace a fuse, ensure that all active power sources (batteries) are disconnected first.
Battery Charger Board
Siemens GSM Cellular Radio
Component layout of the Siemens GSM radio is illustrated in Figure 1-6. The SIM
card slot can be accessed by pressing-in the circular extraction button located
immediately to the left. When a valid SIM card has been inserted, the status LED will
turn solid green after application of power and registration with the carrier.
Additional information on the Siemens radio is available at the web site
www.siemens.co.uk/ or the distributor web site www.tdc.co.uk/.
Power should always be disconnected from the Siemens M20
Terminal while a SIM module is being removed or installed.
Siemens GSM Radio
IMU-II/s Terminal Block Connections
Terminal block connections for the IMU-II/s product are shown in Figure 1-7.
Tamper detect is wired at the factory to the magnetic tamper switch mounted on the
enclosure housing. In addition, the alarm input is wired to the low battery detect
alarm (lantern cells) from the battery charger board. This leaves two inputs that are
available for field connections. These inputs (positions 3, 4) can be defined as either
alarms or pulse counting channels by changing the configuration memory of the
IMU-II/s. Instructions on how to change the EEPROM configuration memory
contents is provided in Chapter Three.
Terminal Block Connections
Enclosure Mounting Holes
Mounting hole locations for the enclosure are illustrated in Figure 2-1. Each of the four
mounting holes is of 0.312” (7.9mm) diameter.
Enclosure Mounting Holes
GSM Antenna Connection
It is important that an antenna be connected to the GSM radio prior to the application of
any power sources to prevent internal damage to the cellular radio. Radio transmitters can
experience a condition known as ‘standing waves’ if they are not terminated into a proper
An external antenna is recommended, and the cable length should be sufficient to feed
into the right-hand fitting on the bottom of the enclosure and route to the GSM antenna
connector shown in Figure 1-2. The connector type is a special ‘FME’, and a suitable
antenna must be equipped with a male fitting.
Tie wraps on the mounting plate are intended to secure the FME connector and provide
some measure of strain relief. Additional strain relief can be achieved if the fitting at the
bottom of the enclosure is tightened sufficiently to grip the antenna cable.
Install Lead Acid Battery
If the lead acid battery is not already installed, refer to Figure 1-2 for the mounting
location. Observe the polarity of the wires to ensure that the red wire attaches to the ‘+’
terminal and that the black wire attaches to the ‘-‘ terminal.
If the lead acid battery has been out of service for some period of time, then it is
recommended that it be charged for 24 hours prior to installation. A constant
voltage charger is recommended with an output in the range of 13.0 to 13.6 volts.
Install 6V Lantern Cells
Lantern batteries install at the left-hand corner of the enclosure as illustrated in Figure
1-2. Observe the wire polarity when attaching the leads to ensure that the red wire
attaches to the ‘+’ terminal and that the black wire attaches to the ‘-‘ terminal.
Install Lithium Battery Pack
Install the battery pack into the plastic ‘clip’ holder at the location illustrated in Figure
1-2. Attach the electrical connector from the battery to either J2 or J3 on the IMU-II/s. A
good battery pack will result in the green LED of the IMU-II/s to begin flashing. A dim
or completely dark LED may be due to a weak or dead battery.
Chapter Five describes the steps necessary to place a call after the batteries have been
installed. Refer to Chapter Three first however if the EEPROM memory has not yet been
configured or Chapter Four if the central computer account is not prepared.
IMU-II/S EEPROM Memory Configuration
Configuration of IMU-II/s EEPROM memory
Programming and configuration of the IMU-II/s memory is accomplished using the MP
programmer software and serial interface cable. This process is detailed below:
a) Personal computer loaded with MP programmer software version 2.03 or greater.
b) PC to Remote Interface cable, p/n: 2005-0019C-001. Reference Figure 3-1 below.
b) IMU-II/s data collector with battery power applied.
PC to Remote Interface Cable
a) Attach the 9 pin D-sub end of the PC to Remote Interface cable to an available
communications (COM) port on the computer.
b) Start the MP programmer software with the command "MP COMx IMU/S" where
COMx is either COM1 or COM2.
c) Attach the opposite end of the PC to Remote Interface cable to the 4-position
connector at the bottom left-hand corner of the IMU-II/s board (J8).
d) Select the appropriate action by pressing F2, F3 or F4. A typical configuration
screen is shown in Figure 3-2.
10/10/00 METRETEK Programmer, Version 2.03 12:00
Dual Port IMU/S. . . <No > Default . . . <xxxxxxxxx> Timeout . . . [xx] SECS
Port 1 Port 2
Remote Unit ID . . . . . . . . .  [xxxxxx]
Telecom Mode . . . . . . . . . . < Originate > <xxxxxxx>
Phone Number 1 . . . . . . . . .[ 3212599700 ]
Phone Number 2 . . . . . . . . . . . . . . . . . . . . . . [xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx]
Dialer Type . . . . . . . . . . . . .<Tone> <xxxxx>
Alarm String Download . . .<No >
Input Type . . . . . . . . . . . <Data > <Alarm >
Alarm Description . . [xxxxxxxxxxxxxxxx] [xxxxxxxxxxxxxxxx]
Data Bits . . . . . . . . . . . . .<8> <x>
Stop Bits . . . . . . . . . . . . .<1 > <xxx>
Parity Type . . . . . . . . . . .<None> <xxxx>
Max Line Speed . . . . . . .<2400 > BPS <xxxxxxx> BPS
Answer Ring Count (1-15) . . . . . . . . . . . . [ 1]
Primary Call Retry Count (1-15) . . . . . . . [ 5]
Primary Call Retry Rate (1-15) . . . . . . . . .[ 15] 1 Minute Increments
Secondary Call Retry Rate (1-15) . . . . . . .[ 2] 1 Hour Increments
Time-Tagged Interval Size . . . . . . . . . . . .<30> Minute (s)
F1 = HELP F2 = READ F3 = MODIFY F4 = PROGRAM Esc = QUIT
Example MP Programmer Screen.
A brief description of each field is provided below:
Dual Port IMU/S
Always select 'NO' to disable the dual port feature.
Remote Unit ID
This is a six digit identifier that is used by the data collection software to distinguish the
individual field devices. Legal entry values are 000000-FFFFFF (hexadecimal notation).
Sequential numbering is not required, nor is it a requirement to use any of the
hexadecimal digits 'A, B, C, D, E, or F'.
For battery powered applications, this should always be set to ‘originate’.
Phone Number 1
This field is where the phone number of the central computer site is placed, and has the
capacity to hold 31 digits. Special control characters can also be entered as below:
• The sequence ‘Cxxxx’ (‘x’ represents a numerical digit) is a special code that
provides the PIN number to the GSM cellular radio. Not all installations require
this PIN number however, as this will depend of the type of cellular service that
has been negotiated with the carrier. If a PIN code is used, it should always follow
at the end of the telephone number.
• A 'Dx' character set inserts a delay where the duration of the delay is determined
by the value of 'x' in units of ½ seconds. Examples of typical delay values are
D1 = 0.5sec, D4 = 2sec, D9 = 4.5sec.
An example phone number is "D4 3212599700 C3024".
| | |____ Cellular PIN number code.
| |____ Phone number
|_______ Creates 2 second delay
This selection has no effect, and normally defaults with the ‘Tone’ option.
Alarm String Download
This parameter should always be selected as ‘No’.
Permits selection of data or alarm functions for Input-1 (left-hand column position of
Figure 3-2) and Input-2 (right-hand column).
This field has no effect.
Serial port setting for data bits; should always be set for '8' to ensure proper operation.
Serial port setting for stop bits; should always be set for '1' to ensure proper operation.
Serial port setting for the parity type; should always be set for 'None' to ensure proper
MAX Line Speed
This setting should always be selected as ‘2400’.
Answer Ring Count
This setting should always be selected as ‘1’.
Primary Call Retry Count
Defines the number of times that the IMU-II/s will make call retry attempts at the
primary call rate before switching to the secondary call retry rate. A value of '5' will serve
most applications well.
Primary Call Retry Rate
Determines the time interval between attempting call retries. A value of 10 or 15 is
suitable for most systems. Solar or battery powered cellular systems should use the less
aggressive rate of 15 to permit the battery time to recover from the previous call attempt.
Secondary Call Retry Rate
After the primary call retry count has expired, the secondary call retry rate determines the
interval between successive attempts in 1-hour increments.
Time Tagged Interval Size
Determines the resolution of the interval data collected on the pulse data inputs. Possible
selections available are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60 minutes, with 10, 15, 30,
60 being the most commonly used. A finer resolution permits short term fluctuations to
be more easily observed, but has the negative side effects of longer communications
duration, associated shorter battery life, and more expensive telephone charges.
After programming the IMU-II/s with the MP software and cable, remember
to disconnect the cable before attempting to make a call. Communications will be
disrupted if the programming cable remains attached.
Central Computer Account Configuration
The central computer operator must enter an account into the DC2000 system for each
remote that is installed. This is accomplished using the Remote Unit Configuration
When adding the account the product type must be set to IMU.
After the unit has been installed, the data input meter readings can be
synchronized with the meter index in the field. This is accomplished by forcing
a call from the remote unit and recording the current field meter reading. This
meter reading must then be entered at the central computer using the Remote
Configuration application on the Input Description tab.
IMU-II/S Alarms – Status Flags
The IMU-II/S has various alarms and status flags. If the IMU-II/S is enabled to auto-dial,
the alarm condition will cause the IMU-II/S to immediately place a call to the central
computer. Status flags will not trigger a call to the central computer, but they will be
reported on the next communications with the central computer. These alarms and status
flags are designed to inform the computer that an exception condition exists at the
IMU-II/S. If a Metretek protocol connection is established these alarm/status flags will
be sent to the host computer using Metretek protocol. If the IMU-II/S fails to connect
using Metretek protocol, the IMU-II/S will default to the transparent mode and the alarms
and status flags will be sent to the central modem as an ASCII string at the beginning of
communications. Preceding these alarm strings the IMU-II/S will transmit its unit
identification number using the format listed below.
This unit ID number is read from the IMU-II/S’s configuration memory and is
programmed by the Metretek programmer. If the IMU-II/S is enabled for dual port
operation, it will call phone number 1 when all alarms except customer alarm 2 occurs.
A customer alarm 2 occurrences will cause the IMU-II/S to call phone number 2. If the
IMU-II/S is calling phone number 1, it will report Port Unit ID. If the IMU-II/S is calling
phone line number 2, it will report Port 2 Unit ID. If the IMU-II/S is not enabled to auto-
dial, the active alarms will be reported at the next scheduled communication with the
Table 4-1 shows the ASCII string that is transmitted for each specific IMU-II/S
status/alarm flag when in transparent mode. The alarm strings that are transmitted when
a customer alarm 1 or customer alarm 2 occurs are programmable via the programming
port by using a laptop PC and the Metretek Programmer software. These programmable
alarm strings can be up to 20 characters in length.
Transparent Mode Alarm Maintenance Commands
The alarms reported in transparent mode must be cleared by the central computer by
transmitting the ASCII string “+-+clralms” to the IMU-II/S. The alarms can also be
cleared by sending the IMU-II/S the string “+-+ca” or “+-+CA”. The IMU-II/S will
respond with an “OK” message after the flags have been cleared. If the IMU-II/S is
enabled for auto-dial and an alarm occurs the clear alarm string must be sent to the IMU-
II/S to acknowledge the receipt of the alarm. If the call is aborted and the alarm has not
been cleared the unit will enter the call retry mode and call back at the programmed call
retry interval. The IMU-II/S will remain in the call retry mode until it receives the clear
alarm string from the central computer.
After connection with the IMU-II/S and the initial transmission of the alarms, the central
computer may request that the alarms be retransmitted by sending the scan alarms
command (“+-+SA” or “+-+sa”) to the IMU-II/S. The IMU-II/S will respond by re-
transmitting the unit ID and alarm messages.
Table 4-1 IMU-II/S Alarm and Status Flags
ALARM ASCII STRING DESCRIPTION
LOW *LOW BATTERY ALARM* The IMU-II/S’s battery is nearing a discharged
BATTERY (*see note 2) condition and the battery needs replacement. The
IMU-II/S checks its battery voltage level at the
beginning and end of each call.
CALL RETRY *CALL RETRY ALARM* The IMU-II/S’s previous call was unsuccessful.
(A call is attempted again at the primary retry rate
for the number of times specified for a primary
retry in the IMU-II/S’s configuration EEPROM.
Then calls are placed at the secondary retry rate
specified in the IMU-II/S’s configuration
EEPROM until the call is successful.)
UNIT RESET *UNIT RESET ALARM* The IMU-II/S module is forced to restart because
it is being installed or a program interruption has
INPUT 1 *CUSTOMER ALARM 1* Normally open Customer-specified alarm,
ALARM activated by closing the circuit.
(see note 1) (TB1-3 to TB1-5)
Only available if input 1 is programmed to be an
INPUT 2 *CUSTOMER ALARM 2* Normally open Customer-specified alarm,
ALARM activated by closing the circuit.
(see note 1) (TB1-4 to TB1-5)
Only available if input 2 in programmed to be an
TAMPER *TAMPER ALARM* The normally closed tamper alarm indicates that
ALARM the tamper circuit has been activated. (A door
switch that is normally closed is opened.)
CUSTOMER *CUSTOMER ALARM* Normally open alarm input. Activated by closing
ALARM the circuit.
(TB1-1 to TB1-2)
Note 1: The ASCII alarm strings that are reported for Input 1 Alarm and Input 2 Alarm
are programmable using the Metretek Programmer.
Note 2: Due to battery voltage fluctuations over temperature and load, we recommend
that the IMU-II/S’s battery not be changed until the IMU-II/S has reported a low battery
for 7 consecutive days.
Metretek mode vs. Transparent mode
The IMU-II/S has the ability to communicate in one of two modes, Metretek or
Transparent. Metretek communications mode is used to communicate with the central
DC2000 system using Metretek protocol. Transparent mode is used by a remote
computer to communicate directly with a DTE device attached to the IMU-II/S DTE
serial port (TB1-8 to TB1-13).
After the initial connection with the central modem, the IMU-II/S will attempt to
communicate using Metretek protocol. If the IMU-II/S is unable to establish a Metretek
connection within 3 seconds, it will default to a transparent link, simply connecting to the
central computer to the DTE. In this Transparent mode, the central computer will have
direct control over the DTE via the IMU-II/S.
Initiating a Call to the Central Computer
A final check-off of the items below should be performed first before attempting a call:
GSM cellular radio has a valid SIM module installed.
An external antenna is connected to the GSM radio.
EEPROM configuration parameters have been programmed into the IMU-II/s.
All pulse/alarm input wiring connections to the terminal block are complete (this is
not mandatory however to place a test call).
At this point, it is safe to begin attaching leads to the multiple battery sources. A good
sequence for applying power is the following:
1) Lead Acid Battery
2) Lantern Battery Cells
3) Lithium battery pack.
Sequence of Operations During a Cellular Call
Immediately after the IMU-II/s is powered, the Program Monitor LED will turn on solid
green while a RAM memory test is being performed. In the unlikely event that the RAM
test should fail, the LED indicators will turn solid red. Normally the RAM test will pass
and the IMU-II/s will proceed to attempt to place a call into the central computer.
Serial data between the IMU-II/s and the GSM radio will be exchanged to verify the
status of the radio and to provide the phone number so the call can be initiated. The small
indicator light on the GSM radio housing should be illuminated solid green at this stage.
After 20 or 30 seconds, the red Carrier Detect (CD) LED will light to indicate that it has
made a connection with the MODEM at the central computer site.
Receive Data and Transmit Data lights will flash alternately as data is being exchanged.
Time duration during this phase depends on the amount of information being transferred.
When the call is finished, the bottom two red LED’s will illuminate solid to indicate that
the communications session was successful. These will then extinguish shortly thereafter.
It is normal for the LED indicators to remain lit for several minutes after
the initial application of power to the IMU-II/s. Afterwards; the LEDs
will only light while a call is in progress to conserve battery power.
Whenever the IMU-II/S detects a TAMPER alarm (enclosure door
open), the LEDs will be activated for 4 ¼ minutes. To re-enable the
LEDs after the 4 ½ minute period has expired, close and reopen the
Basic Trouble-Shooting if Call Attempts Fail
If the call did not complete as expected, the following items should be rechecked:
a) Verify that the GSM radio is authorized for use and that it is within ‘earshot’ of
the nearest cellular base station antenna tower.
b) Check the EEPROM configuration memory of the IMU-II/s to determine that the
phone number is correct and that the PIN number is valid. (Some installations
may not require a PIN number entry for operation).
c) Verify that the DC-2000 account is setup correctly with the correct unit-ID,
interval size, etc.
d) Measure the battery voltage levels on the lead acid and the lithium pack while a
call attempt is being made. A fully charged lead acid battery will measure about
12.4 and the lithium pack about 3.5 volts.
e) In addition, a quick verification that all the wiring is proper can be performed
using the wiring diagram in Appendix ‘C’ as a reference.
Securing the Enclosure Door
After verifying that all components of the installation are functioning properly, the door
can be secured with, padlocks or lead seals on the enclosure latches. In addition, the
fittings at the bottom of the enclosure should be tightened to provide strain relief for the
GSM Phone Registration Problem
GSM cellular calls cannot be initiated, and the indicator light on the radio housing does
not illuminate solid green as expected.
a) Verify that the SIM module is a 3.3V type phase II.
b) Check if a PIN number is required to make the phone operational. This may or
may not be required depending on the contract arrangement made with the
c) Check the antenna, antenna cable, and the connector for any signs of damage or
Call retries and aborted calls are a frequent event at certain sites.
a) This may be due to marginal reception with the GSM base station tower.
Relocation of the field unit antenna to a higher elevation and/or away from
obstructions will often enhance the performance.
b) It is possible that the telephone company line or the MODEM at the central
computer site has a problem. Substitution of these items with alternates can help
to narrow down the cause.
The GSM phone is known to be operational, but the IMU-II/s is unable to place calls.
A visual inspection of all wires, connectors, etc., can often reveal the source of the
problem. It is especially important to check that the RS-232 interface board is fully seated
on the IMU-II/s circuit board since a minor ‘bump’ could work it out of position.
Short Battery Life
Lantern battery cells die at premature rate at a certain site despite having a similar
configuration to other units.
a) Frequent call retries or alarm events may be consuming the lantern cells. With
battery powered cellular products, it should always be the goal to minimize the
number of calls made.
b) The lead acid battery that is maintained at a full charge level by the lantern cells
may be defective. Old age with lead acid cells (approx. 5 years) is a common
symptom, with the battery not being able to hold a charge and therefore wasting
c) A small interval size for the pulse inputs will result in more data being collected,
and therefore longer duration cellular phone calls. Trade-off decisions must be
made between the desired data resolution and the acceptable battery life.
GSM Radio Never Powers-Up
The IMU-II/s board will attempt to make a call when the technician triggers an alarm
input, but the GSM radio indicator light never shows any activity.
1) Using a DC voltmeter, verify that the voltage across the lead acid battery
terminals is approximately 12.4 volts. If not, suspect either the lead acid battery or
the lantern cells.
2) Place voltmeter leads on the battery charger board terminal block across terminals
4 & 5. Pressing on the toggle switch should cause 12 volts to appear at these
points. The GSM radio light should also show some activity regardless if the radio
is authorized or not. If this test fails, a blown fuse may be the cause. Refer to step
3) Before testing the fuses on the battery charger board, it is necessary to disconnect
both the lantern battery cells and the lead acid battery electrical terminals. Set the
multi-meter to the ohms test mode and test across the ends of each fuse. A
resistance of 5 ohms or less can be considered normal. Replacement fuses should
always be of the same type and rating.
4) If pressing the toggle switch results in power being applied to the cellular radio,
but the IMU-II/s is still not able to bring-up power to the radio during a call,
check the VSW wiring connection. This connection routes from the IMU-II/s
board on the J9 connector to terminals 2 & 3 of the terminal block on the battery
charger board. Refer to the wiring diagram in Appendix ‘C’ for additional
ASCII Abbreviation for the term American Standard Code for Information
Interchange. ASCII characters include all the upper and lowercase
characters found on a keyboard as well as numbers, symbols, and special
Baud Serial data transmission speed, normally associated with RS-232 type
communications. Common usage of this term is to equate it with 'bits per
second'. A typical ASCII character may contain 8 data bits, 1 start bit, 1
stop bit, and no parity. For a 2400bps data rate, this yields an effective
transfer speed of 2400bps/10bits = 240 characters per second.
Carrier A signal that is transmitted by a MODEM and is often (but not always)
used to carry information. Information is inserted into the carrier signal
with modulation schemes that include frequency and phase elements.
CCITT An advisory committee to the International Telecommunications Union
that makes recommendations on telecommunications issues.
DCE Data Communications Equipment. A device that provides for the
establishment of a communications link, signal conversion of data, and the
termination of the communications link.
DTE Data Terminal Equipment. A device that generates information for
transmission over a communications network.
EPROM Erasable Programmable Read Only Memory, these hold the operating
program for the microprocessor and retain the information even if power
is lost. Devices with transparent windows can be erased with ultraviolet
light and then reprogrammed
EEPROM Electrically Erasable Programmable Read Only Memory, these devices
hold information in a permanent manner even if power is lost. Erasure and
programming of new information is entirely electronic and does not
require a window and ultraviolet light. Metretek products use EEPROMs
to retain information such as the telephone number, interval size, etc.
GSM Global System for Mobile telecommunications.
Hexadecimal A number system based on 16 possible values per digit position. These
include 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E, and F. A byte has two digit
positions permitting a range of 00 to FF, which yields a decimal
equivalent value range of 0 to 255.
IMU-II/s Industrial Metering Unit - II / serial. This data collector product has two
pulse inputs (can be reassigned as alarm inputs), one dedicated alarm
input, and a tamper detect input.
LED Light Emitting Diode, these are in common usage as indicator lights due
to their high efficiency and long life.
MODEM Acronym for Modulator / Demodulator. This device converts information
presented on its port (normally RS-232 port) into a signal that can be
transmitted/received over the telecommunications network.
PCB Printed Circuit Board, in this context refers to a board populated with
RS-232 A serial data communications interface that was published in 1969 by the
Electronic Industries Association. Transmission of data is accomplished
by level switching with +3V to +9V representing zero and –3V to –9V as
SIM Subscriber Identity Module.
Operating Temperature Range (excluding the GSM radio)
-30° to +70° C (-22° to 158° F)
Height: 17.5 inches (44.4cm)
Width: 14.75 inches (37.5cm)
Depth: 6.63 inches (16.8cm)
12.5 lbs (5.67 kg) without batteries.
27.0 lbs (12.2 kg) with all batteries installed.
Lantern Cell Batteries (2):
6V lantern battery, Eveready 521 or equivalent.
Nominal capacity = 40Ahr.
Lithium Cell Battery:
3.6V lithium battery, Metretek P/N: 1011-0022B-001.
Nominal capacity = 13Ahr.
Lead Acid Battery:
12V sealed rechargeable lead acid battery.
Nominal capacity = 7Ahr.
Recommended replacement interval = 5 years.
Data Storage Capacity:
28K RAM available for Time Tagged Interval data.
Serial Interface Bit Rate:
Programmable for 300, 1200, or 2400bps. Recommended setting = 2400.
Serial Interface Data Bits:
Programmable for 7 or 8. Recommended setting = 8.
Serial Interface Stop Bits:
Programmable for 1, 1.5 or 2. Recommended setting = 1.
Serial Interface Parity:
Programmable for Even, Odd, or None. Recommended setting = None.
Data Input – 1:
Form-A type switch input, a transition to closed causes a pulse to be recorded or an alarm
to be triggered. Input is programmable for either the data or alarm functions. Minimum
contact time is 40ms, maximum pulse frequency is 10 hertz.
Data Input – 2:
Form-A type switch input, a transition to closed causes a pulse to be recorded or an alarm
to be triggered. Input is programmable for either the data or alarm functions. Minimum
contact time is 40ms, maximum pulse frequency is 10 hertz.
Dedicated Form-A alarm input with a minimum contact time of 63ms. A switch transition
from open to closed will be recorded as an alarm.
Tamper Alarm Input:
Dedicated Form-B alarm input with a minimum contact time of 63ms. A switch transition
from closed to open will recorded as an alarm.
SIEMENS GSM CELLULAR RADIO SPECIFICATIONS
(Additional specifications can be found in Appendix – D)
FME antenna jack (female)
Antenna Connection Impedance:
R.F. Transmit Power:
1 watt (cw), 2 watts peak
SIM Card Interface:
3V type Phase II
Operating Temperature Range: (M20 Terminal)
-20° to +55° C (-4° to 131° F)
The seller warrants its hardware to be free from defects in material and
workmanship under normal and proper use for a period of 12 months from the date
the hardware is shipped from Metretek, Incorporated. The seller’s sole liability and
the buyer’s sole remedy for any breach of the foregoing provision is, at the seller’s
option, the timely no-charge repair or replacement of any defective hardware or part
that Metretek inspects and finds reasonable evidence that a defect in material or
workmanship exists. The buyer shall provide the labor required to remove the
defective hardware and install its replacement at no charge to the seller. The
equipment will be shipped to the seller at the buyer’s expense. The replacement or
repaired equipment will be shipped to the buyer at the seller’s expense.
Warranty claims to be honored under this warranty must be made promptly. Such
claims shall specify the nature and details of the claim, the date that the cause of the
claim was first observed, and the affected equipment’s unit serial number. Defective
equipment shall not be returned to the seller’s factory without prior authorization
from the seller. A copy of the claim’s documentation must be attached to the
defective equipment and sent to the seller’s manufacturing facility. Defective
components replaced under this warranty shall become the property of the seller.
The seller makes no representation or warranty other than those set forth in this
agreement. THE WARRANTY STATED HEREIN IS EXPRESSLY IN LIEU OF ALL
WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO,
ANY EXPRESSED OR IMPLIED WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE. SUCH WARRANTY CONSTITUTES
THE ONLY WARRANTY MADE BY THE SELLER WITH RESPECT TO THIS
AGREEMENT, THE EQUIPMENT UNITS, OR THE SERVICES TO BE SUPPLIED
HEREBY. THE SELLER SHALL NOT BE LIABLE FOR ANY INCIDENTAL OR
CONSEQUENTIAL DAMAGES OF ANY KIND.
This warranty will not extend to equipment subjected to accident, to misuse, or to
alterations/repair not made and documented in writing by Metretek.