Merlin Universal Input Digital Indicator

Merlin Universal Input Digital Indicator

With Simple Setup via USB

Additional information

Weight 0.646 kg
Dimensions 9.5 × 12.4 × 6.4 cm
Power Supply

UV – 24-250V AC / 19.5-250V DC

Output Options

– No Output
R2A – 2 x Relay Outputs, 1 x Analog Output

Share This Product

What it does

The Merlin accepts one of several popular input signal types to display.

It doesn’t matter what voltage you’re using

Sending to another country with a different voltage? Worried about the unit getting fried? Relax.

The Merlin accepts 24-250V AC or 19.5-250V DC making it a truly universal unit suitable for anywhere in the world. So now there’s no need to stock separate high voltage and low voltage units, now you just need one: this one!

No more accidental changes during handling!

With programmable panel meters one slip of the finger can be the root of many headaches. But with the Merlin you don’t have to worry! There’s no buttons on the unit so you don’t need to stress about accidental parameter alterations during handling. Instead set-up is via your PC using a USB connection.

So simple it doesn’t need a manual

It doesn’t get much simpler than this. No more reading hefty manuals or frustrating delays. You’ll experience the rare joy of getting your application up and running sooner and afterwards you’ll wonder why you’ve tolerated difficult setups all this time.

You don’t need to power it up to configure

Yes, you heard us correctly. You can configure the unit directly using the Merlin’s excitation voltage. You’ll be surprised how easy we’ve made it.

The Merlin process indicator accepts analog inputs from a range of industrial sensors, including: process, temperature, flow, frequency, and voltage from 200mV to 300V. It features a wide range power supply that suits both AC mains and 24V DC applications, and supplies the excitation required for common sensors and transmitters.

The Merlin digital panel meter can be scaled into any engineering unit, and the result displayed on the large 0.8” 4 digit super-bright LED display. Auto ranging is available to increase the dynamic range of viewable data. The Merlin R2A adds two Form A 3 Amp relays for a variety of control and alarm functions, and a 4-20mA active output for retransmission to PLCs and SCADA systems.

This panel indicator has been designed for harsh industrial environments. With an IP65 sealed bezel and extensive testing of noise effects to and beyond CE requirements, the Merlin LED panel meter provides a tough and reliable application soluti

Universal input:

  • Temperature input : Thermocouple (B/E/J/K/N/R/S/T types), RTD (Pt100/Pt1000), NTC (10K Beta 3984/3435)
  • Process input : Current (0/4–20.000mA DC), Voltage (various ranges from -10V to 300V DC)
  • Digital input : NPN (2 and 3 wire)/PNP (2 wire only) open collector (0–2000.0Hz)
  • Potentiometer input : (<1kΩ to 20kΩ)
  • AC current sensor input : (ACCS-010/ACCS-420)

Other features:

  • Universal AC/DC power supply (24-250V AC, 19.5-250V DC) – no header adjustments required!
  • Optional relay outputs, ideal for alarming and simple on/off control
  • Optional isolated 4–20mA output, making the Merlin ideal for use as a PLC/SCADA accessory
  • 22V excitation to power two wire transmitters
  • Flexible 32 point linearization table

Easy, USB Powered Programming

The unit boasts a 1 minute setup time using the Define Toolbox configuration software. All functions and features are explained expertly in the dynamic sidebar help – perfect for the novice starting out who can use it to learn about industrial sensors and applications, or the expert who wants to save commissioning time.

Define ToolBox Configuration Software

Try Before You Buy!

Use the product simulator inside our free ToolBox software to demo how this instrument works.

Bridge Key Required!

In addition to this software a Bridge Key is required for the configuration of this product.

You must order one unless you already have one from a previous product purchase.

Compare digital indicators

Brand & Model Power Supply Input Analog Out Relays UL Listed? Price
Red Lion PAXD000 85-265 AC or 11-36V DC DC 0/4-20mA or 0-10V 2 Yes $403
Precision Digital Trident 85-265 AC or 12-36V DC Universal 4-20mA 2 Yes $349
Newport iSeries – i8A00 90–265V AC or 12–36V DC Universal 0/4-20mA or 0-10V None Yes $295
Define Instruments Merlin 19.5–265 (AC/DC) Universal 4-20mA 2 Yes $249
5 Year WarrantyRCM E2180CEC UL US Listed


Universal Input

Number of universal inputs: 1

Accepts Thermocouple, RTD, NTC, Current, Voltage, Digital Pulse, Potentiometer & AC Current sensor (See below for full specifications for each input type)


Power supply: 24-250V AC / 19.5-250V DC, 47-63Hz, 6VA max

Isolation: 2,300Vrms for 1min to all inputs and outputs

Thermocouple Input

Thermocouple types:

K: -328 to 2502°F (-200 to 1372°C)

B: 752 to 3272°F (400 to 1800°C)

E: -328 to 1472°F (-200 to 800°C)

J: -328 to 1832°F (-200 to 1000°C)

R: -58 to 3200°F (-50 to 1760°C)

S: -58 to 3200°F (-50 to 1760°C)

T: -328 to 752°F (-200 to 400°C)

N: -328 to 2372°F (-200 to 1300°C)

T/C lead resistance: 100Ω max

Cold junction compensation: -14 to 158°F (-10 to 70°C)

CJC error: < ±2°C

Accuracy: E, J, K, N, T: < ±1°C. B, R, S: < ±2°C.

Ambient drift: E, J, K, N, T: < ±0.05°C/C. B, R, S: < ±0.2°C/C.

Sensor break output drive: Function high upscale/low downscale

Response time: 400msec

RTD Input

RTD input type: PT100 or PT1000 DIN 3-wire type (2-wire can be used with off set trim)

Lead wire resistance: PT100: 50Ω/wire max. 0.02% FSO off set error per Ω of lead resistance mismatch PT1000: 20Ω/wire max. 0.002% FSO off set error per Ω of lead resistance mismatch

Sensor current: 0.3mA nominal

Sensor break output drive: Function high upscale/low downscale

Accuracy: Better than 0.2°C

Ambient drift: <0.007°C/C

Response time: 400msec

NTC Input

NTC: 10K Beta 3984: -67 to 257°F (-55 to 125°C) 10K Beta 3435: -58 to 230°F (-50 to 110°C)

Response time: 100msec

Accuracy: Better than 0.4°C

Ambient drift: <50ppm/°C

Current Input

Range: 0/4–20.000mA

Excitation: +22V DC, 25mA max

USB programmable zero: 0–±99% of span

Field programmable span: 1μA–24mA DC

Input impedance: 10Ω

Max over-range: 50mA DC continuous

Linearity & repeatability: <±0.02% FSO typical

Ambient drift: <50ppm/°C

Response time: 100msec

Voltage Input

Ranges: Millivolts: ±200mV, –200mV to 1V Volts: 0–10V, ±10V, –10 to 30V, 0–300V

USB programmable zero: 0–±99% of span

USB programmable span: 95% of FSO

Input impedance: 1MΩ min

Linearity & repeatability: 0–10V: <±0.05% FSO 0–300V: <±0.1% FSO. All other ranges: <±0.02% FSO typical

Ambient drift: <50ppm/°C

Response time: 100msec

Digital Pulse Input

Frequency range: 0–2000.0Hz

Sensors: Open collector NPN (2 and 3 wire)/PNP (2 wire only)

Excitation: +22V DC, 25mA max

Response time: 100msec

Software modes: General frequency, Flow rate (pulse), or RPM (pulse)

Linearity & repeatability: 0.05%

Ambient drift: <50ppm/°C

AC Current Sensor Input

Sensor type: Current transformer (ACCS-420(-L)/ACCS-010)

Amperage range: Header selectable ACCS-420/010 = 100/150/200A ACCS-420-L = 10/20/50A

Overload: (continuous) ACCS-420/010 = 175/300/400A respectively ACCS-420-L = 80/120/200A respectively

Output: (Representing 0–100% of full scale input range) ACCS-420 = 4–20mA DC loop powered ACCS-010 = 0–10V DC

Power supply: ACCS-420(-L) = Loop powered, 15–36V DC ACCS-010 = Self powered

Accuracy: 1% of full scale

Response time: 250ms (10–90%)

Isolation voltage: 2,000V

Frequency: 50–60Hz

Potentiometer Input

Potentiometer input: 3-wire

Excitation voltage: <1kΩ low pot; 1–4kΩ med pot; 4–20kΩ high pot

Potentiometer resistance: Variable

Field programmable zero: 0–90% of span

Field programmable span: 0.1–100% Linearity & repeatability

Linearity & repeatability: <±0.05% FSO typical

Response time: 100msec

Ambient drift: <50ppm/°C

Relay Output

Number of relay outputs: 2 (R2A model)

Relay output type: Form A

Isolation: Isolation to sensor and user input commons: 2,300Vrms for 1min. Working voltage 240Vrms

Contact rating: One Relay energized: 3amps at 120/240V AC or 28V DC (resistive load). 3amps max total current with both relays energized

Life expectancy: 100K cycles min at full load rating

Analog Output (Retransmission)

Number of analog outputs: 1 (R2A model)

Analog output type: Self-powered (active) 4-20mA or 20-4mA DC

Isolation: Isolated to sensor and user input commons

Isolation test voltage: 1,400Vrms for 1min. Working voltage 125V.

Accuracy/repeatability: 0.05% of FSO

Resolution: 1μA

Max output drive: 20mA (600Ω max load at 12V DC)

User Input

Number of user inputs: 1 (R2A model). Can be programmed for manual relay reset, latching, or zero functions

Max continuous input: 20V DC

User input isolation: Not isolated to sensor input common


Define ToolBox: USB programmable using Define ToolBox (Bridge Key required)


Display type: 0.8″ (20mm) red LED, 7-segment characters

LED indicators: 2 x setpoint indicator LED’s (R2A model only)

Digits: 4

Full scale range: -1999 to 9999:


Casing: Panel mount enclosure. Installation Category II, Pollution Degree 2. Flame resistant. Panel gasket and mounting clips included.

Ingress protection rating: IP65 indoor use. (Face only, when mounted according to manufacturer’s instructions)

Dimensions (H x W x D): 1.89 x 3.74 x 2.44″ (48 x 95 x 62 mm)

Weight: 6.87oz (195g)

Cutout area: 1.77 x 3.62″ ±.02 (45 x 92mm ±.5)

Space behind panel: 3.15″ (80mm) minimum space required behind panel (includes space for connectors/wiring)

Environmental Conditions

Operating temperature: 14 to 122°F (-10 to 50°C)

Storage temperature: -4 to 140°F (-20 to 60°C)

Operating humidity: 5-85%RH max (non-condensing)

Altitude: Up to 2,187yd (2,000m)

Certifications & Compliances

EN 61326-1: Immunity to Industrial Locations

Emission: CISPR 11 Class A (EN 61326)

Safety requirements for electrical equipment for measurement control and laboratory use: EN 61010-1 General Requirements, EN 61010-2-030 Particular Requirements for Testing and Measuring Circuits

UL listed: File Number E473114


Merlin Manual 23V04, 06-Sep-2023 | (1.8MB)
Merlin Datasheet 17V04, 19-Jun-2017 | (221 KB)


Define ToolBoxDefine ToolBox

Smart, simple software to program your non-Zen series products

Use Define ToolBox software to program your non-Zen series product via your PC. It configures:

ToolBox offers a simple interface for connecting to your compatible device, and a range of flexible configuration options, including an extensive library of pre-calibrated ranges and linearization tables for advanced scaling.

Define ToolBox Configuration Software

Order Codes


-UV 24-250V AC / 19.5-250V DC
Output (Optional)
-R2A 2 x relay outputs (PLUS 1 x User input for relay reset or latching)
1 x 4-20mA analog output
Sample order codes: MER-UV or MER-UV-R2A

All prices are in US Dollars. For pricing in other currencies, please contact us.