Adiabatic temperature in Abaqus VUMAT

Hi All ,
I found  simple VUMAT from Abaqus manual.It is based on
Von Mises plasticity and gives stress components, vonmises stress
and plastic equivalent strain.

I want to include the adaibatic temperature that rises/falls along the deformation in adiabatic
analysis.From a general book, i found that temperature-rise during deformation comprising

plastic strain1 to plastic strain 2 is given by:

Integral of stress between the strain limits,multiplied by a constant.

That constant = Inelastic heat fraction divided by product of specific heat and density.

So, i defined a new variable stateNew(k,6) for instantaneous
temperature and want to add two lines in the end of the subroutine which gets updated
at each increment. 

temprise = constant*deqps*equivStress
stateNew(k,6) = stateOld(k,6) + temprise

"deqps" is the change in plastic equivalent strain from the previous
increment to present increment and equivStress seems to be vonMises
stress as calculated in the subroutine.

Please indicate if I am right in implementing the temprise equation?
Also,should it be the "current vonMises stress" or the difference in
vonMises stress from previous increment and current increment?

Regards,
Sonia