Turns out that the VXI-USB bus timing is slightly different than all the other controllers and exposed a bug in the VXI card I was troubleshooting.
Hi K. Coggins,
You mentioned that you are having a similar issue. Does this mean that you are also receiving corrupted data when using a VXI-USB device? Does this also occur when calling viMoveIn? Have you tried any of the suggestions Logan S. made above? The more information you can give me about the errors you are having, as well as the hardware and software you are using, would be extremely helpful.
For more information on VXI bus timing, take a look at the following links:
I hope this helps a little. Give me as much information as possible, and I will look into the issue a little further.
Message Edited by Lauren L on 10-22-2007 08:36 AM
The issue K. Coggins is referring to involves ViIn16 calls returning bad data. We have a HP xw4400 PC running XP and NI-4.0 software. The chassis is a Racal 1261b with a NI VXI-USB slot 0 controller. The instrument having issue is an Ascor switch matrix. This instrument uses a controller card in the VXI chassis to control relays in a separate card cage (Not VXI). The secondary card cage consists of 13 slots which are all populated. The bad data problem does not occur when only 11 slots are populated. I'm suspecting that there is a memory management issue here but do not know how to proceed.
Ni-Spy reports no errors. This instrument does not have any problems when running with a MXI-2 controller.
Any suggestions would be great.
Hi M. Beene,
What kind of 'bad data' are you getting specifically? Is it providing you with unexpected data, or is it skipping data points? The more information you can give me, the better chance I will have at figuring out the issue.
USB devices do not have the same transfer rate as a MXI connection, so it sounds like the most likely possibility is that it is getting backed-up when you have so many relays in the cage. The USB device has a max transfer rate of 32 Mb/s, while MXI-2 has a max transfer rate of 38 Mb/s. As far as I can see this is the most likely cause of the issue you are seeing. Is it necessary that you use a USB device, or could you set up your system using the MXI-2 cable you tested with?
I hope this helps a little, but if you need more specific information, give me a little more information on the data you have been receiving.
Since I do not have all the details of the application, my best recommendation is to take a look at the data sheet for each of the products. Because the system operates correctly when using a MXI-2 connector, it certainly makes it seem that the issue lies in the performance specs for each device.
I will continue to look into this, but at the moment, my best suggestion is to take a look at these.
The customer has decided to move everything to MXI-2 so this will be a non-issue. No point in you spending any more time on it.