GPIB Read.vi does not output right data?

[detech]

I have two HP E4401B spectrum analyzers, bought at the same time. I developed a labview program to control them. The program works well with one spectrum analyzer (A), but not another one (B). I found that GPIB Read.Vi does not output right data for B. It is just crazy characters like #428049j%9rmß9x"9�È,9�Þô9tÈù9

[Noel]

Based on the data you included in your question, I would guess your (A) analyzer is set to return data in ASCII format while your (B) analyzer is set to return data in binary format. Typically data encoding format is settable on many instrument. Therefore, you can set (B) to return data in the same format as (A). Alternatively, the binary format is probably an IEEE 488.2 definite length block format. You might choose to return data in binary format for improved performance. Below is a link to some examples for parsing definite length block format:

Waveform Encoding and Scaling for Instrumen
t Control Applications