weird effect of NI SPY

[schao]

Hi, all,

I am a prober/handler GPIB driver developer. Recently, I encountered some weird issue with NI SPY.

In my code, the following statement will send a command from tester to handler, the error handling statement will be executed when there is a bus error.

 ibcmd(0, cmd, 2L);
 if (ibsta & ERR)
 {
  printf("SQR waiting Error\n");
  ibonl (dev, 0);
 }

When the code is run at the production line, it is observed that: when NI SPY is open and capturing, the statement will never be executed, which means no error occurs. However, without NI SPY, the ERR handling will occurr like 5 in 300 runs.

Anybody has such experience? what is the effect to run NI SPY during GPIB communication?

Thanks.

regards,

Shi Chao

[Albert.Geven]

Hi

One effect is: it slows down the communication a bit and that can be sufficient for this difference with and without NIspy

[schao]

Hi, Albert,

Thanks for the advice.

If the slower speed helps to relieve the bus error, does it mean that I can lower the GPIB bus speed setting in MAX tool to get better performance?

regards,

Shi Chao