PXIe 2593-Relays are not responding

[hwfyn]

Hi,

I have PXIe 2593 on PXIe 8370 controller. Until today, 2593 responds all commands correctly, I can hear the "click" sound from relays while switching but today it starts to not responding commands. On MAX Test Panels, it is seen that switching occurs correctly but actually it does not switch on hardware. Even if I change the position of switch, the hardware(relays) are stucked. I can not hear "click" sound from relay. What can be the problem? 

Thank you.

[hwfyn]

I checked relay counts and the highest count is about 12000 so expexted life time is much longer. 

I want to check the relays whether they work or not but I could not find any way. NI Switch Healt Center checks NI Switchblock Cards not PXI devices. Is there any way to check whether relays work correctly or not?

[Andy-K]

Hi hwfyn,

If you have a hand held DMM or another method of checking resistance, you can measure the resistance between two channel connections.  You can use this method to determine if the relay is open or closed.  You can then change the switch position in software and check to see if there is a change.

Another thing to consider is possible software issues. To test this, I would try and connect the PXI chassis to a different PC with just the basic switch software that allows you to use test panels in Measurement & Automation Explorer.

Finally, before the relay stopped clicking, what was the voltage, current, and frequency of the signal you were sending through? 

[hwfyn]

I do not have a DMM. What are other methods to test the relay connections?

I use an agilent signal generator to test the program that I generate using LabVIEW. The voltage that signal generator provided was 1 V peak to peak and frequency was in the 1 MHz-5 MHz range. I am not sure about the current  but I was using the switch with PXIe 5122 digitizer and the input resistance of the digitizer was set to 1 megaohm by default so the current should be extremely low. 

[Now_With_Underscores]

Hey hwfyn,

Sorry to hear you're having problems operating your 2593.  Can you clarify if all relays are not operational, or just particular ones?  If all of the relays are nonfunctional, have you recently changed any of the software in the system?  Particularly, the DAQmx driver version, but also any other changes are worth noting in your next reply.

Do you have any other NI switch modules you can place in the suspect system to see if they are operational?

If the 2593 is showing up in MAX and passing self-test, and the soft front panel indicates the relays are changing position, I recommend placing the module in a different slot of your PXI chassis, which will force the SW to re-enumerate the module.  If the relays still don't operate - but SW indicates they are changing position - I'd verify whether or not the ribbon cable on the 2593 that connects the two PCBs is properly connected.

I'll also second using a DMM to test the physical connections... if you're not able to find one, you can also kludge together a test circuit using a flashlight, duct tape and some jumper leads... or buy a disposable DMM online... everyone should have a DMM ;).

[hwfyn]

Hi John,

2593 does not respond any connection commands. I think this means that all of the relays are non-functional. There is another thing which can be useful to solve the problem is that one connection is stucked closed-particularly ch0-com0-. However, on switch soft front panel, the ch0-com0 connection seems to be open. 

I have not change any of the software system.

I do not have any other switch modules.

The situation is exactly what you said "If the 2593 is showing up in MAX and passing self-test, and the soft front panel indicates the relays are changing position...". I ca tey changing the slot of the 2593 and check the ribbon cable.

When I said "I do not have a DMM", I particularly talked about NI DMMs. I can find a disposable DMM like in your link. How can I check physical connections using DMM? 

By the way, thank you 😃

Ali

[Andy-K]

Hi Ali,

I think confirming the relay positions with a DMM is a good next step. Most DMMs like the one that John linked will have a continuity mode. Typically in this mode if the signal can pass through from one lead to another then it will beep or show some sign on the display. This will tell you if the connection is open or closed by connecting the two leads of the DMM to the different pinouts of the switch.

[EricS.]

Hi Ali,

Below is a picture showing the ribbon cable that John was talking about.  Ensure that this ribbon cable is securely fastened to the connector.  If this ribbon is not making a good connection, none of the relays will operate.

Can you confirm that none of the relays operate?  Or do all of the relays operate correctly except for channel 0?

[hwfyn]

Hi Eric,

we checked the connections of the 2593 via a DMM. we observed that ch0-com0, ch4-com0, ch8-com1 are shorted(in continuity mode we heard a beep). however, when we connect the input signal to ch4 and com0 to digitizer we cannot see the signal in NI Scope whereas when we connect input to ch0 and com0 to digitizer we can see the signal in NI Scope. 

ribbon cable seems to connected properly but we will check it tomorrow more carefully. I say tomorrow because we use NI devices at work so we can only apply your suggestions in work hours and due to the time difference between you and us, when you start your day, we are nearly at the end of the day 🙂

By the way, th signal generator I use at most generates 20 V peak-to-peak which means it generates lower current values than the maximum switching current of the switch(specifications document says it is 0.5 A).

Thank you for your interest. 

Ali

[EricS.]

Hi Ali,

The relays used on the 2593 are latching relays, which means they stay in their current position until they are driven to a different position.

Because of this, I am not concerned at all about the fact that some channels are shorted and others are open.  As you can see from the internal schematic (found here), it is easily possible for both ch0 and ch4 to be connected to COM0.

What matters is whether or not continuity is made or lost when you use the NI Switch Soft Front Panel to connect different channels of the multiplexer.  Do you hear any relays clicking when you change which channels are connected in the soft front panel?  Try to connect every channel of the Dual 8x1 mutliplexer topology.