PC is not able to detect chassis/ Detection is very unstable

[HelloHelloHello]

Hi All,

I have a cDAQ-9178, CompactDAQ chassis (8 slot USB). It has been working perfectly well until recently. 

My computer suddenly can't detect it one week ago and I solved the problem by unplugging and plugging back the power cable. A few days later, the detection went very unstable and I need to unplug/plug the USB cable out/into USB ports every time it went undetected in order to keep data collection going. The unplugging and plugging USB cable helped to switch from undetectable to detectable cases. Now, two days earlier, the system just went  undetectable and I have tried unplugging/plugging both power cable and the USB cable. On the chassis, there's a green like are on 'power' but a yellow light on 'active' instead of 'ready'. Sometimes, it suddently went detectable but then it went undetectable for hours before it went detectable again for a minute. 

I'm just wondering if any of you guys might have a better idea of what happened to the system and what might cause the unstable ( undetectable most of the times) situation. Thank you!

[Captain_K]

Hi HelloHelloHello

Was there an event last week that occurred around the same time the chassis first went undetected, like a power surge?

Can you tell me what OS you’re running, what version of DAQmx you have, and when the device isn’t being seen in MAX, can you still see it in Windows Device Manager (assuming you’re on a Windows machine)?

Also, have you tried plugging the chassis into a different computer to see if the problem follows?

[HelloHelloHello]

Sorry for the late reply. There's no power surge. However, I did re-wire some connections. Could a possible mis-connection leads to unstable detection? (Wouldn't a mis-connection leads to a complete undetection?) Most of the times when I unplug and then replug the USB connections back to computer or back to chassis (keeping computer side unchanged), it went detected again. but sometimes, it just remain silence for days before it came back again. 

Im using Windows. Whenever it went undetected, the system went undetected in instrumentation and configuration. It also went undetected in control panel as well. 

I have not tried plugging into a different computer, but computer USB ports work fine with other USB devices. 

[Captain_K]

I don’t believe an incorrectly wired connection would cause this sort of issue, but I’ve seen crazier things with electronics.

To test this, can you remove all the modules from the chassis and plug it in?

If the chassis shows up, unplug it and plug it back in a few times to try and make sure that it’ll keep showing up. Then add the modules back in individually to test each one.

If the chassis doesn’t show up, I’d recommend testing it on another computer. I know you said the USB port works, but I still think this would still be a valuable step.

[HelloHelloHello]

Hi Matt,
Thanks for your reply. I removed all modules from chassis, but that does not seem to improve the detection of chassis. I also used my own computer (without LabView and NI-max installed), but my computer seem to have problems with detection of chassis as well (no device showing up in control panel). Any idea why would that be? Thank you!

[HelloHelloHello]

A few more details: 

1. The computer I am currently using to collect data is behaving similarily with or without module on chassis. For a long time, It keeps not showing up disregard whether I unplug or plug in USB port many times. Suddenly it shows up in the NI-MAX and then I was able to unplug and plug in USB port in order to keep disappeared chassis coming back up. (Once it is responsive and before it went to sleep again, Unplugging and plugging USB port once it went undetectable help bring the system detectable, not continously though.Once it went to sleep, the only thing I can do is to wait until it shows up again automatically ) 

2. I plugged the USB to my personal computer. It's able to show up and disappears in the control panel when it's reponsive (Not continuous detection similar to when I use the computer I used to collect data) and it remains silence when it goes to sleep. So, similar cases disregard whether I uses my own computer or uses the actual computer to collect data. 

Does that mean there's something wrong with chassis itself? It was working perfectly steady until one day I found the power light was not on.(I don't think there's a power ourage though and even if so, why would that specific power outrage causes problems with chassis?) Then I unplugged and plugged in back the power cord, the light went back on and it was able to be steady for that time and became unsteady a day later. (It's always green light on power, amber light on active and no light on ready) The unsteadiness kind of got worse (e.g. went to sleep for days disregard whether I unplug/plug power cord, usb connections) recently. 

[Case_in_Point]

Have you tried a different USB cable to connect to the device? That kind of unreliable connection sounds like possible cable issues. Also, just to be clear, you'll want to at least install DAQ-mx and MAX to try and test out device connection. Basically, no point is seeing if a device is detected when you don't even have the driver installed.

Cason

Applications Engr., NI

[JÞB]

Time to pull out the FAQ's again

Spoiler

Yes, I've seen this before- encluding answering a forum post where the OP was sitting next to me but did not know I was Jeff·Þ·Bohrer  He actually asked the supervisor if he knew anything about Windows power options because "Some guy on the Forums suggested checking them."  So, I got to demo the recommended solution

USB Plug-n-Play Devices (Windows)

In this topic we will discuss some of the common problems that have been observed using USB devices with LabVIEW on Windows operating systems.  Many of these points are also applicable to other environments but the examples will be use the Windows 7 OS.

FAQ 1 : My USB device stops working unexpectedly.

The first thing to look at is the OS power saving options.  There is a global trend towards developing "Green" electronics and energy star ratings are getting fairly common.  "If its not being used shut it off" is nothing new.  Cavemen learned how to bank a fire to preserve energy that would otherwise be wasted.  Likewise, the Windows OS has a power saving feature to shut down power to the USB hubs when no user activity is present.  In Automated systems this feature can cause problems since removing USB hub power will shut down the USB device.   Solution: Use the device manager to change the USB hub Power Options.

FAQ2: I set the power options and my device connection is still unreliable: Remember, those computer USB ports are often the cheapest that can be mounted on the chassis and share the PC system power supply to supply USB Power. Most uses of USB are temporary connections like a thumb drive or a camera.  These connections do not require high reliability since the user is right there interacting with it.  Power surges and fault tolerance at worst cause the operator to retry the data transfer.  Automated systems require a bit more robustness.  Solutions:

1) ALWAYS use an external self powered hub.  Perform your engineering due diligence and inspect the devices specifications too- If you can't find them for that device that should clue you to seek an product from a vendor that WILL publish their specs.

2) High noise environments require the use of ferrites on the USB cable- and don't buy the cheapest cable either! The cheap ones are poorly shielded.  

3) PROTECT the HUB connections-  If you have a USB2.0 device and Joe User plugs in a 1.0 device in a open slot managed by the same hub- Bingo every port on the hub may back convert to USB1.0.  WORSE there are a lot of damaged or marginally engineered USB devices out there.  Joe User's device may cause power fluctuations when it is inserted or removed from the hub just don't let it happen!

FAQ3: I am testing USB devices and the OS can't find them anymore.

This is a Plug-n-Play feature that deserves some exposure.  When you connect a P-n-P device the OS remembers its serial number in a HKEY (Hive-Key) registry entry.  This is helpful when (for example) you want a specific instrument, Say an NI-USB-6008, to show up as a DAQmx Device with VISA Alias "MyDAQ1" every time it is plugged it.  On the other hand, If you want to test a line of USB-Serial converters this can be problematic since the P-n-P driver will mount the first serial number as "COM3" and the next as "COM4" add infinitum until the enumerator controller in the registry and VISA recognized aliases get used up.  Solution: Use the Windows registry API and the Hardware Configuration API in LabVIEW to clear unused VISA Aliases and HKEY entries.   Speak with your staff IT professional about HKEY structure and possible side effects before developing a plan to edit registry entries.

---

Pay especial attention to FAQ2.  Get the right HUB, and don't let "Joe User" start sticking his grubby phone charger (or what-not) in the system!

[HelloHelloHello]

Thanks for your reply!
I tried an external self-powered hub but things don't go better. And to be clear, it seems to work a lot better (remain detected for longer) whenever I plug and unplug the USB connection. Is this a problem with chassis itself then?

[JÞB]

Did you check the power management settings?