Error -50150 "Cascade Failure": LabVIEW Bug?

[Paul Champion]

Hello,

I'm new to the forums here, so I apologize in advance for breaches of etiquette or various other newbie actions. 😉

While using the DAQmx Create Channel VI in conjuction with my own custom unit scale, I keep running into a -50150 error for various combinations of slope and y-intercept. I've pared my problem down to the attached VI. As you can see, I'm setting up the linear scale with a slope and y-intercept, and then scaling the original +/- 10V range for an appropriate maximum and minimum. Upon running this VI as-is, I get the -50150 "cascade failure" error. However, changing the y-intercept value to an arbitrarily different value, say 6, causes the program to run fine.

I've noticed that other combinations of slope-intercept also crash the program, and that these combinations usually have a pattern. For example, the (m, b) combinations of

(100,5); (100,20); (100,30); (100,45); (100,55); (100,70); and so on, with the 10-15-10-15 pattern repeating

cause the program to throw -50150 as well. I have not found any values of the y-intercept that cause the program to crash that are not multiples of 5 (although obviously I cannot say conclusively that there are none). I realize that it is all very well for me to claim that this is a software bug and not my fault, but I cannot see any good reason for this to be happening in such an odd way.

I am running LabVIEW 8.2.1, DAQmx 8.5, WinXP SP2, Pentium 4 2.79 GHz, 768 MB of RAM. The hardware involved is an NI cDAQ-9172 chassis with NI 9205, 9263, 9211, and 9211 modules in slots 1, 2, 3, and 4, respectively. Thanks very much for your time.

[Matt_A]

Hello Paul,

This was reported to R&D (# 4C0IH7AH) for further investigation. As a workaround, you can change the 10 and -10 limits to something very near to 10 and -10, like 9.99999 and -9.99999. This seems to resolve the issue and will result in basically the same limits. I have attached a modified VI that demonstrates this change. Thanks for the feedback Paul!

[Paul Champion]

I think I was secretly hoping for a problem on my end; it seems to add more closure when someone tells me I am wrong. 😉 Luckily, the posted workaround works fine for our purposes.

Thanks, Matt!