DAQmx error -51030 when using SCXI

Question

I'm building a test system that is using a PCI-6040E with a SCXI chassis. In the SCXI chassis my customer has a number of boards to do AI, AO and some digital control. I configured DAQmx tasks for the various divisions (one SCXI has TC, another is measuring DC voltages, another is output some DC voltages). I created some "action engines" that perform initializations, placing the "DAQmx task name" into an uninitialized SR, to be used on subsequent calls. What happens is that if I configure each of the DAQmx tasks as a single event "when called" (I can't remember the exact wording) vs HW timed, multiple or continuous) this scheme works, but relatively slowly, pausing a good second in each of the acquisitions sub-vi's, resulting in a 6+ second loop time. If I try any of the other modes I get the -51030 error on the second vi executed (they are in a while loop connected with the error cluster chain). Some of what I'm reading almost sounds like I should open each task, acquired, close task, open next, etc., loop. If so does anyone have any idea of the overhead timewise. This system doesn't need to be terribly fast, but I'm measuring currents that I would like to know within a 100ms if they go way out of limits so I can shut down the offending unit.
As always, thanks in advance for your help
Putnam Monroe
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion

Answer 1

Good morning all,
Essentially I have done what LYu is doing, with a "create a channel" for each the "task types" that are on the Analog In. This allows me to have an idea of where in the returned array each group's data will reside and also to perform the appropriate configuration (Thermocouple, current, voltage and frequency measurements) as I create the "groups", they are all, strictly speaking, the same task, but I wasn't able to find a way to easily build the task in MAX, it starts by having you determine which kind of task (Analog in, out, etc.) and then what type (temperature, current, etc.) which precludes having multiple types in the task. You can do this in LabVIEW, as described above. Part of my problem is that without the DAQ hardware installed on the machine that you are using to develop you can't set up any of the settings in MAX and unfortunately time on the target system is really at a premium. On my wish list (for quite a while) is the ability to tell MAX what hardware _WILL_ be installed, and have it let you do the configuration stuff. It has all the data for the supported National Instruments HW in its database. I'm not asking for the ability to simulate the HW, just to be able to do some of the configuration stuff. Many of us develop on systems other than the target one, frequently not being able to get on the target until we are ready to integrate the HW and SW. Oh well, maybe in MAX 5.0 and LabVIEW 9.1 ...
Thanks for all the helpful suggestions,
Putnam Monroe
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion