GPIB; Visual Basic

[dreamhawk]

Hi, I use GPIB to control our device (frequency syntheiszer). Under interative control mode,

I can set the frequency to my device (for example 10MHz). The commonds used are:

:ibdev 0 16 0 13 1 0

ud0: ibwrt "F010000000\n"

Then I use the Visual Basic programming language as:

Dim Dev As Integer

Call ibdev(0,16,0,13,1,0,Dev%)

Call ibwrt(Dev%,"F010000000\n")

The device can still set to 10MHz. However, if I change the frequence to 20MHz as

Call ibwrt(Dev%,"F020000000\n")

The device are still at 10MHz.

Who knows the answer, I really apprecite it.

[John E]

Hi Dreamhawk
You mention that the command
Call ibwrt(Dev%,"F010000000\n")    works but
Call ibwrt(Dev%,"F020000000\n")    does not.

You also mention
ud0: ibwrt "F010000000\n"    works
does
ud0: ibwrt "F020000000\n"    work?

If not you may try:
ud0: ibwrt "F011000000\n"
and
ud0: ibwrt "F015000000\n"
to move incrementally closer to 20 MHz..


Regards,

[Makoto]

It seems like a string termination problem. 

You are using Visual Basic language, not C/C++.  Therefore you can't use "\n" escape sequence to express control characters such as LF (0x0A).  Instead, you must write:

Call ibwrt(Dev%,"F010000000" & vbLF)

or

Call ibwrt(Dev%,"F010000000" & Chr(10))