L40 Low-Cost, Universal Analog Input Digital Panel Meter

Jumper selectable for DC, AC, Process, Thermocouple, RTD, Thermistor, or Resistance Signals

TDM L40A Universal Digital Panel Meter

User-selectable ranges

  • DC voltage: ±60.0 mV, ±200.0 mV, ±2.000V, ±20.00V, ±200.0V, ±400V
  • DC current: ±20.00 mA, ±5.00A
  • AC RMS voltage: 60.0 mV, 200.0 mV, 2.000V, 20.00V, 200.0V, 400V
  • AC RMS current: 20.00 mA, 5.00A AC
  • Process: 4-20 mA, 0-10V with 15V, 30 mA excitation output
  • Thermocouple types: K, J, E, N, L, C, R, S, B, T
  • RTD types: Pt100, Pt500, Pt1000, Ni100, Ni200, Ni1000
  • Thermistor types: NTC, PTC
  • Resistance: 0-5.000 kΩ, 0-50.00 kΩ
  • Potentiometer input: 500Ω to 20 kΩ

Options

  • 1 or 2 mechanical relays, 8A, 250Vac
  • Isolated analog output
  • RS485 Modbus RTU data output

Standard Features

  • Universal power: 18 Vac/dc to 265 Vac/dc
  • 1/8 DIN case with 3 front panel keys
  • Display: 4 red LED digits, 14.2 mm (0.56")
  • Typical accuracy: 0.2% of full scale
  • Removable screw-clamp connectors
  • External control input
Description
L40A panel meter with instrument panel

Model L40 is a low-cost, universal meter for 65 user-selectable analog input signal types and ranges. These include DC voltage and current, AC RMS voltage and current, process signals (4-20 mA, 0-10V), thermocouple (10 types, °C or °F), RTD (6 types, °C or °F), thermistors (NTC or PTC), resistance (0-5k or 0-50k ohms), and potentiometer inputs. The same meter handles all of these signal types with no need for a plug-in signal conditioner board. The meter's universal power supply accepts voltages from 18V to 265V, AC or DC, so that power can be 24 Vdc or AC power in any country. The meter conforms to the popular 1/8 DIN size standard and features four 14.2 mm (0.56") high red LED digits. The display is user scalable for input types other than temperature.L40 range selection jumpers

The base L40, as shipped by TDM, is set up so that a 400 Vac input reads 400. To change to another signal type or range, pry off the meter faceplate, push out the electronics, and place jumpers as illustrated in the manual. The jumper positions are well labeled, and the jumpers have a large, easy-to-grasp handle. Also make software selections using front panel keys. If you want TDM or your distributor to set jumpers and do the front panel programming for you, order the FS option.

Extensive software features add flexibility to this low cost meter. Programmable features include five levels of display brightness, min and max capture, dual scaling selectable by an external control input, a deadband around 0 for AC measurements, a moving average digital filter, a "count by" function, hysteresis for alarm operation, a user-configurable fast access menu, and selectable password protection. Further flexibility is provided by 1 or 2 optional output boards, which can be added at any time.

An Option 1 board can plug into the display board. This can be a single 8A relay board, an isolated active or passive 4-20 mA analog output board, or an isolated Modbus compatible RS485 serial data output board.

An Option 2 board can plug into the Option 1 board if installed. This is another single 8A relay board. For example, this board allows an L40 to have and analog output and a relay output, or to have two relay outputs.

L40 meter circuit boards

If only a single meter is to be stocked for a large number of applications, the low-cost L40 is your choice. While this meter does not match the high accuracy, speed and programmable features of our series, it is perfect for many panel meter applications.

Specifications

DC Voltage & Current

Range Resolution Input Resistance Max Signal Accuracy
±60.0 mVdc 0.1 mV 1 MΩ 3 Vdc < 0.25% FS
±200.0 mVdc 0.1 mV 10 kΩ 30 Vdc < 0.20% FS
±2.000 Vdc 1 mV 100 kΩ 100 Vdc < 0.20% FS
±20.00 Vdc 0.01V 1 MΩ 150 Vdc < 0.20% FS
±200.0 Vdc 0.1 V 12 MΩ 800 Vdc < 0.20% FS
±400 Vdc 1 V 12 MΩ 800 Vdc < 0.20% FS
±20.00 mAdc 0.01 mA 4.7 Ω 25 mAdc < 0.15% FS
±5.00 Adc 10 mA 20 mΩ 7 Adc max 7 sec < 0.25% FS

AC RMS Voltage & Current

Range Resolution Input Resistance Max Signal Accuracy
60.0 mVac 0.1 mV 1 MΩ 3 Vac < 0.3% FS
200.0 mVac 0.1 mV 10 kΩ 30 Vac < 0.3% FS
2.000 Vac 1 mV 100 kΩ 100 Vac < 0.3% FS
20.00 Vac 0.01V 1 MΩ 150 Vac < 0.3% FS
200.0 Vac 0.1 V 12 MΩ 800 Vac < 0.3% FS
400 Vac 1 V 12 MΩ 800 Vac < 0.3% FS
20.00 mAac 0.01 mA 4.7 Ω 25 mAac < 0.5% FS
5.00 Aac 10 mA 20 mΩ 7 Aac max 7 sec < 0.5% FS

Process Signals

Range Scaling Input Resistance Max Signal Accuracy
4-20 mAdc -1999 to 9999 4.7 Ω 25 mA < 0.15% FS
0-10 Vdc -1999 to 9999 1 MΩ 25 Vdc < 0.20% FS

Platinum and Nickel RTD Temperature Probes

RTD Type Range °C Range °F Excitation Accuracy
Pt100 -200 to 700°C -328 to 1292°F < 900 µA, 2 or 3-wire < 1°C
Pt500 -150 to 630°C -238 to 1166°F < 90 µA, 2-wire < 1°C
Pt1000 -190 to 630°C -310 to 1166°F < 90 µA, 2-wire < 1°C
Ni100 -60 to 180°C -76 to 356°F < 900 µA, 2-wire < 1°C
Ni200 -60 to 120°C -76 to 248°F < 900 µA, 2-wire < 1°C
Ni1000 -60 to 180°C -76 to 356°F < 90 µA, 2-wire < 1°C

Thermocouple Temperature Probes

TC Type Range °C Range °F Accuracy
Type K -100 to 1350°C -148 to 2462°F < 3°C
Type J -100 to 1200°C -148 to 2192°F < 3°C
Type E -100 to 1000°C -148 to 1832°F < 3°C
Type N -100 to 1300°C -148 to 2372°F < 3°C
Type L -100 to 900°C -148 to 1652°F < 3°C
Type T -100 to 400°C -148 to 752°F < 3°C
Type R 0 to 1768°C 32 to 3214°F < 3°C
Type S 0 to 1768°C 32 to 3214°F < 3°C
Type B 700 to 1828°C 1292 to 3322°F < 5°C
Type C 0 to 2300°C 32 to 4172°F < 5°C

NTC Thermistors (negative temperature coefficient)

R25 Values Beta Values Resolution Accuracy
100Ω to 100.00 kΩ 2000 to 5500 1° or 0.1°, °C or °F < 1.5% of reading

PTC Thermistors (positive temperature coefficient)

Main Series Range °C Range °F Accuracy
KTY-121 -55 to 150°C -67 to 302°F < 1°C
KTY-210, KTY-220 -55 to 150°C -67 to 302°F < 1°C

Resistance

Range Resolution Bias Current Accuracy
0 to 5 kΩ 1 Ω 926 to  64 µA < 0.5% FS
0 to 50 kΩ 10 Ω 86 to  20 µA < 0.5% FS

Potentiometer

Potentiometer Range Default Scaling Potentiometer Resistance Accuracy
0 to 100% 0 to 100.0 500Ω to 20 kΩ < 0.5% of FS

Applicable to All Signal Types

Display
Digital readout 4 red LED digits, 7-segment, 14.2 mm (.56") digit height, 5 brightness levels
Display range -1999 to 9999
Update time 300 msec
Sensor break indication Display of "h.ovr" for overrange, "h.udr" for underrange
Indicator lamps 2 red LED alarm indicators
Power
Universal voltage 18 to 265 Vac/dc
Power consumption < 1.5W meter only, < 2.5W meter with options
Isolation 2500 Vrms
Excitation output 5V or 15V @ 30 mA (jumper selectable)
Analog Output (AOT option for slot 1)
Output level 4-20 mA, active or passive (selectable at connector)
Maximum load 350Ω active, 700Ω passive
Scaling Zero and full scale adjustable from -1999 to +9999 counts
Accuracy < 0.5% FS
Update time 400 ms
Isolation 1000 Vdc
Relay Outputs (RL1 option for slot 1 or RL2 option for slot 2)
Relay type Single 3-contact relay (NC, NO, common)
Current rating 8A at 250 Vac
Isolation 2500 Vrms
RS485 (RS485 option for slot 1)
Protocol Modbus RTU
Programmable addresses 1-247
Supported function code 4 = "read the register"
Data rates 9600 or 4800 baud
Isolation 1000 Vdc
Signal Connections
Dimensions
Environmental
Operating temperature 0°C to 50°C
Storage temperature -20°C to 70°C

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