OOPS Your right. I see it is a VISA error. I am reading data from a serial port and putting that on a shared variable. There must be somthing wrong with the timing of the read from the instrument. I will take a close look at that.
I thought that looked like an insturment specific error code. The timing of the device storing readings and your reading from the port must be a bit off and eventually you wind up filling some FIFO buffer. not really ideal especially, if you are getting old data from the filling buffer and matching that to current temperatures.