Error with Tcl GPIB commands when using variables with SCPI messages

[krusty]

If I were to simply make a call to a power supply such as:

gpib open -address 5

gpib write -message {VOLT 20}

my power supply would set the voltage to 20VDC

However if I were to make a procedure that sets the voltage and pass the voltage value as an argument - then the Agilent instrument gives me an Invalid Character response (code -101).

example:
proc SetDCPower {gpibID DCPower} {
 gpib open -address $gpibID
 gpib write -message  {VOLT $DCPower}
 gpib close
}

followed by a call to this procedure with the following in the same TCL script

SetDCPower 5 15

Other commands such as gpib write -message {POW ON} work fine in a procedure so I know the GPIB address argument works.

I have also output the DCPower argument to the screen and text file - and it looks normal.

Anyone have this issue?

[krusty]

OK. It looks as though the GPIB command will not accept a variable in place of a number regardless of whether it is an argument from a procedure.

I defined a variable:  set ThisIsATest 15

the made a call with it in the same procedure:  gpib write -message  {VOLT $ThisIsATest} and it still fails.

Thus my question is now - can a TCL GPIB command be given with a variable in the SCPI message

[Kyle_M]

Krusty,

Because youre using a third party language to interface with an Agilent power supply, you may have more luck asking this on the TCL developer's site here:

http://www.tcl.tk/community/

Theyre most likely going to have a much more in depth knowledge for how to program and troubleshoot in TCL. 

Regards,

Kyle Mozdzyn

Applications Engineering

National Instruments

[krusty]

Yes I agree, and I have actually posted on one of the services from that web page. However, there were some TCL related questions on this discussion board and thought I would see if anyone else had similar experiences. 

[krusty]

I figured out what the problem was. It had to do with creating a string using the variable prior to sending the command.

[Perry_S]

Hi Krusty,

I am happy that you were able to figure it out!! Excellent!!

Perry S.

[orrca2112]

---

@krusty wrote:

I figured out what the problem was. It had to do with creating a string using the variable prior to sending the command.

---

I know this is an old post, but I was wondering if you could help me.  I ran into virtually the same problem and its had me stumped. I was wondering if you remember how you fixed this.  If so, could you share the code?

Much Appreciation,

CAO

[ianidas300]

Have you also posted your questions to the other forum listed for the third party code?

As stated above:

http://www.tcl.tk/community/