Hi,
I've searched issues related with this topic (mapping signals between Simulink model and LabVIEW),but maybe is better
to open a new issue 
Basically,
I need to send control data from Simulink to LabVIEW model, and give
back resulting data to Simulink to complete
the closed loop control in
this way.
Is that possible to do??
Software configuration
OS : Windows (not an RT target)
LabVIEW 8.6
SIT 5.0
To be more clear I hope the pictures of the next example help.
P control in SImulink:
And a simple model in LabVIEW:

I am not sure if SIT could help me in this
issue, and that's why I've decide to ask you. Maybe is not necesary to
use the SIT, but at the moment I don't have another idea.
So
far I've only conected LabVIEW controls with model parameters of
Simulink bolcks and LabVIEW indicators with model signals of Simulink,
and that not solve my issue.
Thank you for reading.. 
Any help appreciated.
Regards
P control in Simulink:
Fabian León
Certified LabVIEW Associate Developer