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Wireless Data Loggers

Meter-Master Cello


PRESSURE (INTERNAL SENSOR): Absolute pressure. Input range: 0-300 psi, 0-100 m, 0-200 m. Accuracy/resolution: ±0.5% of range. Pressure port: standard quick-fit male probe.

PRESSURE (EXTERNAL SENSOR): Various input ranges, gauge.

COUNT: Counts voltage pulses or contact closures over preset logging interval and stores total as a 2 byte value. Up to 16,383 events may be stored in any one logging interval (max avg. hertz for 15 min interval = 18.2; for 30 min interval = 9.1). Maximum Hertz for 3-channel logger and for channels 2 and 3 on 8-channel logger is 45 Hz; for remaining channels on 8-channel logger, max Hertz is 10 Hz. Typical applications include rainfall and flow recording.

EVENT: Stores date and time of a voltage pulse or contact closure. Preset resolution interval is 1 or 10 seconds (timebase and logging interval (“rate”) are ignored). If there is more than one event within a resolution interval, each event is stored separately with the same time. Events may be very brief but should not repeat at more then 10Hz. Each event represents a quantity, such as a volume of water or gas or millimeters of rainfall. Applications include rainfall and flow recording.

STATE: Stores date, time, and state whenever there is a change in the voltage level (high/low) or contact closure. Uses 2 bytes of memory. State is examined once per timebase; if the state has not changed, nothing is stored. A changed state must be maintained for a preset number of examinations (the debounce period) before a change of state will be recorded. Typical applications include switch condition and overflow operation.

STATE--ALARM ONLY: Same as State recording except functions only as an alarm. When state changes to alarm condition, Cello immediately calls out with the alarm. May be preset to send data also. Typical applications include electrical or overflow warnings.

VOLTAGE (analogue): Stores instantaneous voltage between 0 and 2.54 volts using 1 byte of memory. A voltage sample is taken each logging interval. Raw values are displayed in volts. 0.01 volts accuracy and resolution. Typical applications include temperature, pressure, and 4-20 mA inputs.

FREQUENCY: Counts voltage pulses or contact closures over a typically short sampling period (e.g. 2 secs) and stores average Hertz as a 2 byte value. Maximum input frequency is 16,383 Hz. The sampling period of 1 to 254 seconds is set independently of the logging interval (as part of the Cello’s initial configuration), and one sample is taken each logging interval. Resolution is 0.01% maximum. Typical applications include flow and conditioned 4-20 mA recording.


LOGGING INTERVAL (“RATE”) AND “TIMEBASE”: Both preset from 1 second to 1 hour. All Logging Intervals (“Rates”) are multiples of single Timebase interval. Not used with Event recording.

RESOLUTION INTERVAL: Preset 1 or 10 seconds. Set to 10 seconds unless greater time resolution is required with Event recording, or a Timebase less than 10 seconds is required with other types of recording (rare). 10 second resolution stores one header per day at midnight (times are counted in 10-second intervals from midnight). 1 second resolution stores a new header every 4 hours (times are counted in seconds from header time).

ALARM DIAL-OUT OPTION: Exceeding a channel’s preset high and/or low values causes Cello to immediately call out with the alarm condition. Cello may be set to include the data as well (beginning from prior data download). If the alarm state remains the same, no further alarms are sent. Option for continuous, time window, and profile modes of alarm operation. Option to update data more frequently after an alarm.

THRESHOLD OPTION: Used with Count, Voltage, and Frequency recording to reduce quantity of data. Records events only when value changes from value of prior event by a preset threshold amount. Uses 3 or 4 bytes per event to store both a data value and a time. Threshold option allows, for example, high resolution recording of a meter that runs very infrequently.

DATA STORAGE: Rotating store, or store until full.

MEMORY: Size: 128K, allocable between channels as required, maximum 64K per channel. Memory type: Solid state, non-volatile.


3-CHANNEL CELLO: Channel 1: pressure (internal or external). Channel 2: Count, Event, or State -Alarm only. Channel 3: Count or Event.

8-CHANNEL CELLO: All data formats except pressure are available for each of the eight channels. (However, pressure may still be recorded using Voltage (analog) data format.


TEXT MESSAGE CAPACITY: Logging interval size for 1 message per day without compression: Pressure = 15 min; Flow = 30 min. Maximum interval size for 1 message per day with compression: Flow = 15 min (most likely; depends on top number and range of numbers). Cello information is dialed in separately from data and data header whenever logger recording is turned on.


INPUT PROTECTION: Protected against reverse connection and over voltage.

OUTPUTS: 2 independent digital outputs for transducer power control and alarm signaling (0 and 3 volt levels, active low, 100kW output impedance) 1 fixed output for "0pen collector" signal bias 3 volts, 33kW output impedance.

GSM MODEM: Frequencies: 900 MHz (Vodafone, 02), 1800 MHz (Orange, T -Mobile ), 1900 MHz (U.S.). Integral antenna.

SERIAL PORT: Type: Full duplex, asynchronous. Data Rate: 1200 bps.

CLOCK TYPE: Crystal controlled calendar clock with leap year adjustment. Accuracy: 100 seconds per month maximum error over operating temperature range. Synchronization: Clock minutes and seconds are automatically synchronized to GSM network whenever unit dials in.

POWER SUPPLY: Type: Internally powered by a single lithium battery pack, factory exchangeable. Life: Typically greater than 5 years depending on mode of use (e.g., continuous 45 Hz count logging will greatly reduce battery life). Internal back up cell maintains logging and local communications when main battery pack is discharged.

ENVIRONMENTAL: Operating temperature: 0°F to +120°F (-20°C to +50°C). Protection classification: IP68, submersible to 2.75’ (1 metre).

MECHANICAL: Dimensions: 7.5” x 5.5” x 6” (191 x 140 x 150 mm). Weight: 2.2 lbs (1 kg).

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