PCI CAN Interface & Channel API performance

[nicola_fabbri]

I have a problem with nctInitStart on Channel API because i receive an error messag (0xbff620a1). Description of error is CanErrScheduleTimeout. I need to update evry 10 ms 6 channel ande evry 20 ms 8 channel. CAN speed is 500KBit/s. How can increase the number of transmitted channel and what is the limits?

[BeckyB]

Hello Nicola �

Are you able to communicate with the device using Measurement and Automation Explorer (MAX)? Visit the GPIB Installation/Configuration Troubleshooter for instructions on how to interactively control your device.

You can use the GPIB Analyzer to capture/monitor bus activity. In MAX, select Tools » NI-488.2 » GPIB Analyzer. The analyzer main window appears, containing the Bus Monitor window, the Action window, and a new Capture Display window.

Other helpful GPIB tips:

When using GPIB, it is very important that the correct driver version is installed for the operating system you are running. Click here to view a table of t
he current driver versions by board and operating system.

The maximum separation between any two devices is 4 m and the average separation cannot be greater than 2 m over the entire bus.

A maximum of 15 loads/devices per bus (e.g., one board and up to 14 instruments) is allowed and at least two-thirds of the devices must be powered on.

If these suggestions do not solve your problem, please be more specific about the error message you are receiving. A screenshot would help clarify the situation. Have a great day!

Becky B.
Applications Engineer
National Instruments

[nicola_fabbri]

Sorry but I'm using CAN device not GPIB.
I thik your answer is not applicable on my project.
The problem is when I try to start the comunication with the command nctInitStart().
The error messag appears as described and says that it's not possible to start all the ouput requested with the desiderated frequency. If I decrease the frequency run, or if a decrease the transmitted channel.
Best regards.
Nicola Fabbri

[BeckyB]

Hello Nicola �

I've fowarded your post to the CAN group. In the meantime, try viewing some of the Top CAN Support Solutions.

Becky B.
Applications Engineer
National Instruments

[JoshuaP]

Hey Nicola,

I ran a couple of tests and I was never able to get my program to set an error. I set it up in MAX so that the bus was running at 500 kBits/s. Then I took the LabVIEW shipping example Waveform Output and modified it by copying and pasting the code so that I would have two programs executing at the same time. One was set-up to run at 100S/s and the other rate was setup to be 200S/s. I added 21 channels across two arbitration IDs. Attached is a copy of the program.

This was using a PCI-CAN Series 2 device. If you are using a Series 1 or a low-speed device it might be harder to achieve these speeds. In addition, the Frame API is faster then the Channel API so you might thing about switching to the Frame API.

In addition, your device mi
ght be in an unsafe state, so try rebooting your machine and then run the application.

I hope this helps out.

Joshua P.
Application Engineering
National Instruments