I suggest you to use linux based simulators as it gives realistic results. Because of its reliability, it is world wide accepted. For WSN I use Castalia and ns2. Both are good for WSN. If you are working with MAC layer and energy model go for Castalia or else use ns2 or ns3. 

Hi check the link below for Mannasim

http://www.mannasim.dcc.ufmg.br/

extract the true time software in the following directory C:\Users\(username)\Documents\MATLAB

and the put the file(startup.m) that i have attached in matalb folder also. 

now open matlab and type 

startup 

in matlab command prompt(if no error) type

turetime 

in matalb command prompt. truetime liberary will run.

please replace the directory in first command of startup.m file