hp 8153A display freeze

[echoyf]

I use HP8153A Example.vi to read channel A's data, and the instrument's display show new value at the same time. when I use HP8153A Example.vi with parameter "channel B" to get channel B's data, the display

freeze, remain the last value and not show new powet meters, But the value labview get is right reflecting the optical power change. 

[Tushar_Jambhekar]

that must be happening because you shift from contineous sampling mode to "Sample on demand" mode,keep your Example VI in loop and check if the value is getting updated after each iteration of the loop.