GPIB one byte control

[bartvsc]

I have to control an old instrument with a serie of bytes, in binary format, one at a time.

Whatever I use, (VISA or GPIB 488), there are sent two bytes at a time, instead of one.

Why is that ? How do I prevent that ?  

[Albert.Geven]

Publish your vi and we have a look at it

[bartvsc]

Hello Albert, here is my vi.

[smercurio_fc]

In the future, please post your VI rather than a screenshot. You can't debug a screenshot.

Your use of Format Into String is incorrect.  If you need to send out the bytes one at a time like that then you should be using the Type Cast function:

 

You should also use VISA unless you have a good reason to use the lower-level GPIB functions. 

Message Edited by smercurio_fc on 03-24-2010 09:03 AM

[Albert.Geven]

Or even better use the conversion function "byte array to string", assuming you have a u8 array.

And of course never use wait until multiple ms, because it is used in most NI examples in a wrong way.

Instead use wait ms or hardware timing when needed.

[smercurio_fc]

The Byte Array to String won't work in this case because that will just give you a big long string of multiple bytes, and the user seems to need to send out one byte at a time, for whatever reason. You would have to snip out one character at time from the string inside the loop.

[Albert.Geven]

Hi

You are right,

normally I use a subvi that transforms a byte into a character because we were used tp pascal it is called Char and accepts a byte as input and delivers a one character string at the output. Inside we use build array and array to string.

Nice test to see what is faster but I guess it will be the typecast.