Raytek MM can be calibrated using Field calibration software: MM-FieldCalibration 1_0_7_1.exe

The software can be downloaded from here 

Note : 

  1. MM is default set to 2 wires for RS485 communication. Request you to change the comms settings to 4-wires from the back panel and try again to allow field cal to connect (it needs full duplex comms rather than half-duplex).
  2. If you running Window 7, 8 or 10 then please change the FieldCalibration application compatibility to Window XP, SP3 as given below :