ALTA Resistive Bridge Meter Configuration and Installation Guide

Sensor Overview

The ALTA Wireless Resistive Bridge Meter is a precision analog device that excites a Wheatstone or other resistive bridge with a voltage, measures it across its 3-foot, four-wire lead, and reports the value in millivolts per volt (mV/V).

Types of Bridges

Common Setup (Wheatstone Bridge)

Common Wheatstone Bridge

This setup will measure the voltage across the yellow and white wires as a ratio compared to the voltage excited across the red and black wires. This ratio is expressed as mV/V.

Common Uses for This Type of Bridge Measurement


¼ Bridge:

Quarter Bridge

This bridge has one variable resistor. With three known resistances, the measurement voltage can be used to calculate unknown variable resistance.


½ Bridge:

Half and Diagonal Bridges

A half-bridge (also diagonal) uses two variable resistors. This measurement can be used to calculate the ratio of the two variable resistors to each other.


Full Bridge:

Full Bridge

A full bridge uses four variable resistors, and its measurement can be used to calculate the ratio of the variable resistance to each other.

Other bridge configurations are allowed as long as they meet the following requirements.

Requirements for all bridges:

  • No outside voltage can be applied to the bridge. The voltage to the bridge is supplied by the red (1) and black wires (2).
  • The total resistance from the red wire (1) to the black wire (4) cannot exceed 500k ohms.
  • There must be some resistance between the black and the measurement wires (white and yellow) and between the red and measurement wires. Otherwise, accurate measurements cannot be guaranteed.

Settings to Configure

  • Name—Enter a unique name for your ALTA Resistive Bridge Meter to easily identify it in many iMonnit views and notifications.
  • Heartbeat Interval (Minutes)—Set the expected time between communication from the device to the gateway while in the Normal State and without any data-triggering events.
  • Aware State Heartbeat (Minutes)—Set the expected time between communication from the device to the gateway while in the Aware State.
  • Assessments per Heartbeat—Configure how many times between Heartbeats the meter will check its measurements against its thresholds to determine whether it will enter the Aware State.
  • Aware State—A mode the meter will enter when specific thresholds are exceeded. This allows the meter to operate at higher power consumption only when you are monitoring near-critical application conditions.
    • Below—Assessments below this value will cause the meter to enter the Aware State.
    • Above—Assessments above this value will cause the meter to enter the Aware State.
    • Aware State Buffer—Prevents the meter from bouncing between Standard Operation and Aware State when the assessments are very close to a threshold.

For example: If the Above Threshold is set to 90 mV/V and the buffer is set to 1 mV/V, then once the meter reads 90 mV/V and enters the Aware State, it will remain in the Aware State until the readings drop to 89 mV/V. Similarly, at the Below Threshold, the reading will have to rise 1 mV/V above the threshold to return to Standard Operation.

    • Gain—Controls the range that can be measured. As the gain increases, the measurement range decreases.
  • For example: When the Gain is 1x, the meter can measure -1000 mV/V to 1000 mV/V. When the Gain is set to 2x, the meter can only measure -500 mV/V to 500 mV/V. If it takes a measurement above or below the measurement range, the meter will report an out-of-range error.
    • Noise Rejection—Enables and disables the power noise rejection filters.
    • Synchronize Off (Default)—The next report will occur one Heartbeat after the last report time. This allows devices to self-optimize network traffic patterns and reduce congestion.
    • Synchronize On—Aligns the next report with UTC (Global) time, regardless of the last report time. This allows multiple devices to generate reports in a synchronized manner. Aware State Transitions will still report on a threshold breach, but the following report will return to the next aligned report interval.

Warning: Too many synchronized reports will increase network congestion. We recommend that no more than 10 devices per gateway are synchronized.

For example: The Heartbeat is configured to 60 minutes, and the device reports at 1:47 PM.

If Synchronization is Off, the next reports are expected at 2:47 PM, then at 3:47 PM.

If Synchronization is On, the next reports are expected at 2:00 PM, then 3:00 PM.

List of Meter Scale Settings

  • Type of Bridge / Unit
    • Raw Value (mV/V)
    • Load cell (gf, kgf, tf, N, kN, lbs, oz)
    • Pressure (Bar, kpa, Mpa, kg/cm^2, kg/m^2, PSI, Torr)
    • Displacement (mm, cm, m, in, ft)
    • Torque (N·m, kgf·m, kgf·cm, ft·lb, in·lb)
    • Inclinometer (degree, rad, grade)
    • Strain (με)
  • Capacity
    • The maximum formatted value produced by the meter.
  • Rated Output (mV/V)
    • The Raw Value produced by the bridge at Capacity.
  • Precision
    • The number of decimals to display.
  • Temperature Scale
    • Fahrenheit
    • Celsius

Installation Steps

Note: If this is your first time setting up your Monnit system, you must set up an iMonnit account and connect your ALTA Gateway to iMonnit before registering your sensor. See this article for steps to start: Creating an iMonnit account.

Then, follow these six steps.

Step 1.

Remove the ALTA Resistive Bridge Meter from the package. If installing an Industrial Meter, attach the antenna.

Step 2.

Register the Meter in iMonnit. Only install the batteries once told to do so in iMonnit.

Step 3.

Configure the Meter's Settings and Scale information in iMonnit for your specific bridge.

Step 4.

Determine the Meter’s installation location. We recommend placing the Meter in the location and ensuring it reports to the gateway before final installation. If you’re using an ALTA Site Survey Tool to perform a site survey to determine sensor installation location, see this article.

Step 5.

After verifying that the Meter is communicating with the gateway, mount the Meter using the supplied screws or double-sided tape. Ensure the Meter's lead wires have enough room to mount to the contact points.

Step 6.

Attach the wires to the desired endpoints.

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