Bug in ul.a_out_scan function with USB2627

[DeanYoon]

I am using the USB2627 product from Measurement Computing to control some hardware with Python. However, I have encountered a bug in the ul.a_out_scan function.

The scan options I am using are ScanOptions.CONTINUOUS | ScanOptions.BACKGROUND, and the bug occurs when the rate is 8E5 and the num_points is greater than 5E5. 

Under normal operating conditions, there are no issues. However, when I connect to the PC controlling the USB2627 remotely via Windows Remote Desktop, the background function of the USB2627 suddenly stops, causing AO to stop as well.

I have updated the firmware to the latest version 1.02, but the issue persists. It seems that the bug only occurs when the num_points is greater than 5E5.

I would greatly appreciate any help or advice you could provide on this matter. Please let me know if you need any additional information from me.

Thank you in advance for your assistance.
 

[JRys]

To summarize, your program will stop without remote login if the output scan rate exceeds 800,000 and the buffer size exceeds 500,000. However, if these parameters are not exceeded, it usually runs unless a remote user attempts to access it. In other words, there may be two issues at play.

 

[DeanYoon]

On 8/17/2023 at 12:30 AM, JRys said:

To summarize, your program will stop without remote login if the output scan rate exceeds 800,000 and the buffer size exceeds 500,000. However, if these parameters are not exceeded, it usually runs unless a remote user attempts to access it. In other words, there may be two issues at play.

 

Thank you for your previous response, althogh it did not provide a solution to the issues I am facing.

I would like to clarify some additional ppoints about the bug. Specifically, when the AO scan rate is 8e5 and the number of data points exceeds 5e5, the background scanning function of the USB2627 works perfectly fine as long as I am not connected to the controlling PC via Window Remote Desktop. It is only when I initiate a remote connection that the background scanning fucntion stops abruptly.

Currently, I am operating with a reduced scan rate of 4e5 and a number of points of 2.4 e5, and I am not experiencing any issues-even when connected remotely via Windows Remote Desktop.

Could you please help identify the root cause of this specific issue and suggest any possible solution or workarounds? It is critical for our operations to understand why this is happening and how to fix it.

Please lent me know if you need any more information from my side.

Thank you in advanced for your assistance.

 

Edited August 21, 2023 by DeanYoon

[JRys]

You could make the analog output buffer larger. I've tested a single output channel at 1 MHz with a remote desktop connection and cannot duplicate the problem. The buffer size I used was 100,000. I use VPN to reach my company's servers and have two computers on this network - they are side-by-side in my office.