M642 Real-Resistance Decade Box

Resistance decade box with 100 mΩ - 22 MΩ range and 5W load capacity. Best resolution 1 μΩ, RTD temperature sensor simulation feature.

  • Real resistors switched by relays
  • 14 decade range, resolution from 1 μΩ
  • Custom units and time sequences
  • No residual resistance
  • 5 W load capacity
  • Six different languages

M642 is programmable real-resistance decade for industrial use. Its far-reaching 0.1 Ω - 20 MΩ range (22 MΩ upgrade available), fine resolution, solid 0.02% accuracy and 5 W load capacity will fit any application. Floating output terminals of M6xx decades allow for AC measurements as well, see datasheet for typical frequency responses.

Languages: English, German, Spanish, French, Russian, Czech

User comfort

M6xx series was made to make resistance calibration as easy as it gets. Large LCD shows all related parameters including total accuracy. And there is no residual resistance or hidden absolute error so you don't have to calculate it by yourself, accuracy you see is what you get. And that's not the only thing that firmware sorts out for you. Would you like the resistance shown in temperature units? Distance? Force? RTD and user function will do this for you. Complete recalibration? Ten minutes and off you go.


All decades' functions can be remotely controlled via RS232, USB, LAN or GPIB interface. This way you can introduce calibration/test stage directly into production line of any resistance based sensor and reduce time required for final quality tests dramatically.

Resistance 100 mΩ - 20 MΩ (22 MΩ), resolution from 1 uΩ
max dissipation power 5 W
± 200 ppm / year
Temperature RTD ± 0.1°C / year
M642 Real-Resistance Decade Box high load capacity, 0.1 Ω - 20 or 22 MΩ
M632 Real-Resistance Decade Box high accuracy and temperature stability, 1 Ω - 1.2 MΩ
M631 Real-Resistance RTD Simulator high accuracy and temperature stability, 16 Ω - 400 kΩ
M641 Real-Resistance RTD Simulator high load capacity, 10 Ω - 300 kΩ
RACK M adapter
RACK M adapter
Detachable rack adapter for extra flexibility. (3HE)