Re: SCXI Strain Null.vi throws -10005 error

[RLD]

I understand the usual causes of -10005, but this time things are
different.  I can read the channel with AI SingleScan or with AI Read,
but the same scxi string errors out on SCXI Strain Null.

The only thing that might be unusual is the remote computer is a
PXI-8146.

Also I have not setup any virtual channel or DAQmx Task.  Am only
using the scxi string.

SCXI Strain Null.vi throws -10005 error

[RLD]

I get a -10005 device is invalid error when I try to run SCXI Strain
Null.vi on a SCXI-1520 which is connected to a PXI-6070E.  The PXI is
being accessed via RDA/ethernet from a LV7 Windows computer.

Otherwise the SCXI-1520 can be configured and read without difficulty.

Re: AI single scan and PWM

[RLD]

Thanks for the suggestions.  I was wondering if there was a way to
tell if the counter/timer was in a state where the the pulse
configuration could be safely changed?

There are several examples of coordinating the AI and AO clocks so
that the AO can be updated with out conflicts.  But when I try the
same thing with AI clock and counter/timer clock in an attemp to synch
up the operations, but the same 10609 error occurs.  I've searched the
doc's and haven't found anything to detect when the counter/timer is
busy.  Do you have any ideas for this approach?

Rich

AI single scan and PWM

[RLD]

I'm developing a real-time control loop that reads an analog input to
pulse width modulate a counter/timer.  I've adapted the
PID_control_pwm.llb example from the example database to use AI Single
Scan in the continuous scan mode.  Every time the counter/timer
Counter Control VI runs, it throws a -10609 error (a transfer is in
progress..).  I think this happens because there is only certain times
in the pulse generation cycle that the timer values can be updated.

How do I coordinate timer updates with analog data acquisition?

Rich

Re: AI single scan and PWM

[RLD]

Sarah,

It sounds like you modified pulse width modulator.vi but you only
attached the pidcontrol_pwm.vi.

Can you clarify the difference between program and switch cycle?
I've experiment with Counter Group Config.vi set to retriggerable
pulse generation and in that mode usingswitch cycle always seems to
error out.

Rich

Re: Call Library node with function returning C string

[RLD]

I prefer cautious, (but paranoid might also apply).  I had a bad
experience back in the LV3/4 era when we forgot to size the string
buffer connected to the input side of a string in the CLN argument
list.

Thanks for the clarifications, I will sleep better now.

Rich

Call Library node with function returning C string

[RLD]

I have a DLL function with a function prototype of char *
StatusString( int status );.  The Call Library node for it provides a
LabVIEW string terminal in the upper right corner to which a string
indicator can be wired.  But if the function is passing back a null
terminated C string does LabVIEW magically create the LabVIEW string
data without additional programming by the developer?  This would be
for LabVIEW 6.1.

Rich

Re: Call Library node with function returning C string

[RLD]

Greg,

Can you amplify a bit more?

When a CLN is accessing a function which has a string pointer return
type (as opposed to a pointer in the argument list), the CLN should be
passing back a non-empty string.  I'm hoping you mean that LV will
automatically convert this C string to the equivalent LV string.

Rich