AnsweredAssumed Answered

8757 analyzer display gets trashed

Question asked by eda on Dec 7, 2007

I'm having a problem with an 8757. I have programmed a timed loop to access the 8757 and output the cursor value to me. thisis a power monitoring method that loops every second and executes the following code in the timer loop, where

Send8757String is a function that outputs cmd to the 8757 over gpib

cmd:='FD0;C1;OC';     //read op power
If Not Send8757String (Cmd,1) then Exit;
displayOpPower.Caption:=Copy (Cmd,1,6);  //extract the ampl data from the response
cmd:='FD0;C2;OC';   //read input power
If Not Send8757String (Cmd,1) then Exit;

after several executions of this loop, like at least 10-20, suddenly the cursor information display on the 8757 becomes scattered across the display, some of it appearing at the bottom right of the display and off screen. Also a vertical line appears on the 8757 display in the upper right side.

Executing this loop through my debugger never reveals the problem. it only happens after i let it free run for, like i said, 10-20 iterations when suddenly the 8757 display starts to look garbled as mentioned.  Loop iteration is 1000 ms.

Is this a known one? Is there a fix or some problem with the code i'm sending? 

The code seems to work fine and returns the proper data regardless of the trashed 8757 display

thanks for any input