Messenger Systems - M61 Alarm Monitor

M61 Alarm Monitor
  • Monitors 12 digital inputs (option for 24)
  • Built in GSM (mobile phone) modem
  • Forwards alarms to PC based Messenger Host Station (and to mobile phones via the Host)
  • Makes programmable routine health check test calls
  • Fully reprogrammable over air and locally
  • Simple to install, no maintenance
  • Self contained lithium battery, no need to recharge, 10 year life
  • Main and standby contact numbers
  • Can automatically disable "fluttering" inputs
  • Wall mounting IP66/67  polycarbonate casing
  • (UL94) - other options available on request
  • Test Button

To view a PDF of the M61 Fact Sheet click on the link :: Messenger M61 Fact Sheet



Any equipment with telecontrol output contacts can now be monitored from remote locations when connected to the Messenger product. Messenger monitors up to 12 normally open or normally closed contacts and reports alarm and reset conditions to a remote PC and/or mobile phones by using the GSM (mobile phone) network. Messenger is self contained and requires no external power source.

The Messenger system was designed as a low cost method of monitoring remote sites or processing plant outside normal working hours. Made up of any number of Messenger units communicating over air using mobile phone technology to a central PC which displays incoming alarms and status changes as well archiving and exporting data.

The schematic below shows how the elements of a typical Messenger System fit together.

Gsm Network


Messenger is completely self contained with a built in GSM modem (mobile phone) and 10 year life lithium battery. The battery is sized in order to allow a weekly test call to be made which confirms operational readiness. Messenger is triggered by the operation or reset of the alarm contacts of the equipment being monitored. Messenger then initiates a data call over the PC based Messenger Host Terminal PC. The telephone number of the Host Terminal is pre-programmed into the Messenger and can be edited over air at a later stage without the need for a site visit.

Because alarm and reset messages from Messenger units are formatted and sent using data technology over the GSM network, installation is simple and provides excellent communications coverage. The PC based Messenger Host Station can be used as a site editing suite.

Alarm and reset messages forwarded to Host Terminal/mobile phone(s) include the following information:

  • Location of Messenger unit
  • Type, serial number and details of equipment being monitored
  • Date/Time alarm event occurred
  • Type of alarm (alarm/reset)

The Messenger Host Terminal application alerts users to the alarm and can display the status of related Messenger units (on the same HV circuit perhaps) and alarm and contact histories. Field staff can be automatically sent an SMS text message by the Messenger Host in the event of alarm conditions.

During contact with a Host Terminal the Messenger unit recalibrates its real time clock and updates any operational settings which users may have edited. If for any reason an alarm call fails Messenger has a retry algorithm to ensure message delivery.

Technical Description

  • I/O - 24 Digital Inputs
  • Example Programmable Settings - Host Station number to forward alarms to, Enabling/Disabling of inputs, Software setting, NO/NC for digital inputs, Alarm Text Messages
    Test Call (health check) frequency (default = 7 days)
  • Cable Entry - 1 x 20mm cable gland allowing maximum cable diameter of 13mm
  • Maintenance Interval - 10 years (battery change)

Technical Specification


Standard Modem GSM 900/1800 (dual band) integrated modem. Requires a data enabled SIM card. Antenna On board stub antenna. Can be replaced by external antenna and lead.

Messenger 61 Technical Description


  • Inputs can be wired as either 24 x direct connections of which 12 may be opto isolated inputs.
  • Type Normally Open / Closed is software selectable. Flutter suppression on individual inputs is software selectable if required.
  • Minimum time required to detect input operation (i.e. debounce) 500 ms.
  • Opto isolated inputs 5kV isolation across inputs, 24V nominal (80V-breakdown voltage between live and common).
  • Directly connected inputs Non-isolated, switched to zero volts.
  • Input terminals High Density Connector. Maximum conductor size 24 awg.
  • On board Event Logs Memory 100

Power Supply

  • External Supply NOT REQUIRED
  • Battery specification 36 Ah Double D Lithium 84w x 60h x 36d
  • Current consumption Quiescent: 10 micro Amps (nominal) TX/RX: 200mA to 600mA at 3.6V


  • Rating -  IP66/67
  • Material - Non Flammable Polycarbonate, colour RAL 7035
  • Dimensions - 130mm (h) x 130mm (w) x 75mm (d)
  • Mounting - 4 x M4 (5mm diameter) wall mounting holes. Holes located outside watertight seal. Holes at 115mm vertical and horizontal centres
  • Standard Cable Entry - 1 x 20mm hole fitted with IP68 cable entry gland. Gland accepts cable diameters in range 4mm to 7mm


  • Approx. Weight (inc. modem and stub antenna) 0.7Kg
  • Operational temp range 20C to +55C (GSM Modem) -45C to +60C (Messenger unit)

  • Retry Algorithm (in case of failed calls/busy Host) 10 retries at approximately 1 minute intervals, followed by a 24 hour wait and then starts call attempts again

  • Health Check test call frequency 1 to 99 days and option to disable


Independently Approved

EN61010-1:2001  EN60068-2-1  EN60068-2-2  EN60068-2-3 EN61326:1997

The following are also available :: Messenger Configuration Kit      Messenger RSSI Measurement Kit      Messenger Training