Thanks for your reply. I did some research (trial and error) and realised
that the supplied code could not be correct. Writing a decimal or ascii 4
could not give the required addres of 20 (they must of got confused with
ascii DC4). I then tried the decimal values for 1 to 12 and hey presto!
I've written to B&K with the corrected code, see below. Hopefully they will
make the changes to their manuals. Sorry that you have wasted your time.
ATN True
decimal 20 ( default address of multiplexer )
ATN False
0-12 decimal
ATN True
ASCII character "?" ( or decimal 63 - UNL )
It is correct that the write command sets the ATN. Using the activex control
from component works reduces the code to,
MyIEEE.ChangePrimaryAddress(20)
MyIEEE.write(chr(12))&&ascii char for channel 12
thanks again for your help.
Mike T wrote:
>Denis,>>The B&K example is way too detailed and confusing. Unless you know
the>lower level details of IEEE488 you'd never sort this out. This example>would
be like telling someone what internet data packets are needed to>go to a
website, instead of just saying www.ni.com.>>The ATN line is one of the IEEE
control lines. The GPIB controller sets>ATN true when it transmits an address
or bus management command. >>ASCII "4" with ATN true is LA4, or listen address
4 (not 20). This is>automatically sent by the write command.>>(You can read
about this in the NI488.2 for Windows Online Help, IEEE488>Command Messages.)
>>So the example is assuming that the B&K is set for GPIB address 4.>>Then
the example says "0-12 binary && selects channel">>I can only guess that
" binary && selects channel" is intended as a>comment to you, the reader
of the example. My guess is that all you>send is a single byte, with a "binary
value" of 0 to 12. Since 12 is>obviously NOT a binary number, I think they
mean 0 to 12 decimal:>>0000 0000 0>0000 0001 1>0000 0010 2>....>0000 1010
10>0000 1011 11>0000 1100 12>>In BASIC, or any derivative like QuickBasic
or VisualBasic, you can use>the function CHR$(x) to create a single character
byte with decimal>value of x.>>So if you want to select channel 1, then use
CHR$(1) to generate the>character (byte).>>Then the example says ATN true
and "?" character. Well, that's the UNL,>or unlisten command. This is automatically
sent by the write command.>>So, the ONLY write you would need is>>write (chr$(1))>>Mike>>p.s.
the example does not show how to read the channel. maybe this>device is
so simple that all you do is read and it replies with the data>for the selected
channel. many GPIB devices can reply with various data>so they typical require
that you first write a query, and then do a>read.>>>>Denis wrote:>> >> Hi>>
I want to use GPIB card to control a Bruel & Kj�r multiplexer.>> The example
code I'm given is,>> >> ATN True>> ASCII charater '4'>> ATN False>> 0-12
binary && selects channel>> ATN True>> ASCII character '?'>> >> I've installed
the Olecontrol from component works, and tried the following,>> >> with thisform.IEEE
&& olecontrol>> .ChangePrimaryAddress(20)>> If .isonline()=.F.>> &&error>>
Return .F.>> Endif>> >> write("ATN True")>> write('4')>> write("ATN False")>>
write("0001") && channel 1>> write("ATN True")>> write('?')>> >> endwith>>
>> I'm confused about the ATN(attention line) call. I can see on the instrument>>
that it goes to remote as soon as the first write is executed. The multiplexer>>
is a listener device so the '?' is also confusing.>> >> Anybody got any suggestions.>>>--
>Mike T
