send serial from LabVIEW to 8051 mc

[rockstar31]

Actually wat i need is. My project is online temperature control. I'm receiving my dac value tat means temperature from rtd is getting in LabVIEW using 8051 board. But now I need feedback error voltage to send mc from LabVIEW. Tat means if my condition is true I have to send port on tat means 5v if my condition false I have to send 0v tat means port off

[Dennis_Knutson]

Your question does not seem directly related to LabVIEW or serial communication. You program the micro to send 0/5 volts. What you write to the micro from LabVIEW is up to you and how you write the micro code. Send ascii text (i.e. ON/OFF) that your micro decodes or a single character (i.e 0/1). What have you tried and where are you stuck?