MN4000/MN4100 Modbus registers scaling.
The Modbus register value represents the temperature that a particular pixel in the 80×60 IR is “seeing”
And its value is in Centi Kelvins. ( Degrees Kelvin multiplied by 100, example 293.68K = 29368 cK ) To convert this value to °C the following formula is used:-
°C = Mbreg – 27315 /100
Mbreg is numerical value of the register you wish to convert.
Example Modbus register 40023 has value of 29368
To convert is ( 29368 -27315 ) /100 = 20.53°C
Registers converted in this way will then display the temperature value in °C
If you want to enter a alarm set point into a PLC register then you would need to convert the input value in °C and then have it converted to centi K so that it is in the same format as the camera registers. The formula is:-
PLCreg = ( °C x 100 ) + 27315
Example alarm set point to be set at 46°C
(46×100) +27315 = 31915
31915 is the value that would be entered into the PLC register.