Starting at $192.00

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  • mA, V, RTD, TC, NPN/PNP, potentiometer, & AC inputs
  • Optional 2 relay outputs & 4 to 20mA analog output
  • Supplies 22Vdc excitation (25mA max)
  • 1/8 DIN panel mount
    • Only requires 80mm behind panel
  • Program using free Define ToolBox software download
    • Requires a USB Bridge Key
  • Designed to withstand harsh industrial environments
    • IP65 sealed bezel
    • UL Listed & CE approved
  • 5-year guarantee

What's in the Box

  • Mounting hardware

The Define Instruments Merlin digital indicator is a highly versatile panel meter designed without buttons to avoid the risk of accidental parameter alterations during handling. It features configurable decimal point options that can display a scaled version of input signals in order to show a value that is more relevant to your process.

Optional outputs are available; two 3 Amp relays for on/off control and alarm functions, and a loop powered 4 to 20mA active output for retransmission to PLCs and SCADA systems.

The universal wide range AC/DC power supply suits both AC mains and 24VDC applications. It supplies the excitation required by most common sensors and transmitters and can be used to power up to two wire transmitters without an external power supply. It accepts analog inputs from a range of industrial sensors, including: process, temperature, flow, frequency, and voltage.

Program the Merlin in less than a minute using the free download of the ToolBox software and the USB Bridge Key. The unit does not need to power up to be configured as it uses its own excitation voltage. Each range is pre-calibrated so it can be configured without having a sensor present.

Required Components

These additional components are required for the operation of your product. We strongly advise you to purchase these components unless you already own them or own a suitable alternative.

Define Instruments Bridge Key Communications Kit
PC connection to all USB-programmable Define Instruments, required for Zen, Javelin, Twin Link, Sentry, Merlin, Pathfinder & TM Series
In Stock


Please consider these optional accessories.

Define Instruments ACCS-010 AC Current Sensor
Self powered unit measures and converts a high AC current signal into a 0 to 10VDC isolated output
In Stock
Define Instruments ACCS-420 AC Current Sensor
Loop powered unit measures and converts a high AC current signal into a 4-20mA DC signal
In Stock


This product can be used in the following applications:

Application Notes

Here's how some of our customers used this product.

No Operator Adjustments

The Background: Our customer is an industrial facility that is in the midst of replacing some equipment. They need a number of panel meters to display measurements from a variety of transmitters.

The Problem: The customer has had issues previously with technicians changing the programming at the meter. They want the tools to avoid unwanted tamering.

The Solution: We recommended the Define Instruments Merlin digital indicator which uses a cable and software package for programming and has no local option for programming by machine operators, making unwanted changes in the field impossible without requiring passwords that could be forgotten or lost.

Part Number Price Available
Show Configuration
Base Price
$192.00 6
Show Configuration
Base Price
2 relay & 1 analog (4-20mA) (+$57.00)
$249.00 5

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