booting PXI automatically on reciving a trigger

[Angelantoni]

Hi all

I have 2 PXI which are redundant to each other, i mean if one PXI fails other should boot up automatically. Is this possible in any way?

I dont want to run both the PXI simultaneously, becuse this leads to some other problems.

Thanx for any reply
Regards
Arun

[Teigen]

Arun,

Which PXI controllers are being used? This information will help me to narrow the search for the feature that you are looking for.

Thanks,

Scott T
Applications Engineer
National Instruments

[Angelantoni]

hi

Am using RT PXI 8186.

[Teigen]

Arun,

We currently do not have a way to trigger another controller to take over the chassis in the event that an original chassis fails. However some PXI modules have watchdog timers that will allow them to go into known safe state once communication with the controller is broken. For example a known state for a digital board would be setting the outputs of the digital board to known values once the controller is down.

Regards,

Scott Teigen
Applications Engineer
National Instruments

[Angelantoni]

Hi Teigen

Actually i don't want the other PXI to take control of the chassis, I just need to start or boot a PXI in another chassis itself. I dont have any thing to measure, am using 2 485 COM port modules(NI-PXI 8423)in my chassis, and both PXI chassis have them. These PXI are communicating to other COM based devices, and if one of the PXI fails i want other device to take control and communicate with these COM devices. any idea on how i can achive this?

Thanx for reply
Arun

[JohnM 64]

Hi Arun,

I think there is a way to do what you are wanting, but it will require some programming in your applications. What you can do is have Controller 1 (which is the first master of the system) treat Controller 2 as a slave at first. You can send messages to your devices and receive the data from them on that controller, but also have Controller 1 send a message to Controller 2 every 30 seconds or so (or however long you want). Then if Controller 2 doesn't receive this message after a minute or two, it should know that something has happened to Controller 1 and that it needs to take over the communication.

Hope this helps!

john m
Applications Engineer

[Josh_KNH]

Hi Arun,

John's suggestion is good and is definitely the most straightforward way to get the functionality you need. Because you mentioned that you didn't want to have both PXI chassis powered simultaneously for unspecified reasons, I'll throw out another suggestion which may suit your needs.

Most of the PXI chassis from NI feature a DB-9 connector on the back with connections to the power supply for power monitoring or inhibiting via an external signal. There is a white paper with some details:

Taking Advantage of the Power Monitoring and Remote Power Reset Capabilities of PXI-1000B, PXI-1006,...

Although it refers to some of our older chassis, the feature is found on most all of our newer PXI chassis, and further details can be found in the respective user manual for the chassis you are using.

You would need to feed out a level signal from System #1 into the DB-9 connector of System #2 to inhibit power, but if you are planning to use the PXI Watchdog which fires a pulse if System #1 fails, you may need to build some type of external circuit that can accept a pulse trigger and change the line state of a signal you then feed into the DB-9 on the back of System #2.

Cheers,
Josh H.

[Angelantoni]

HI all

Initially I was planning to do some thing similar to what Jhon had said, but the problem was 2 PXI cannot be switched on while communicating via a single RS 485 bus(4 wire), so I had planned to start another PXI only if one fails.

Also i checked the link Josh had suggested, but my PXI chassis does not have any DB9 connector at the back of the it. I have NI PXI 1031 chassis.

Regards
Arun

[Teigen]

Arun,

To programmatically bootup the PXI controller the remote power option for a PXI chassis with a DB-9 connector as described in the tutorial referenced above would allow this. Once the automatic bootup is initiated you can save a LV vi as an executable and place it in the Startup folder to launch it so that you can take over communication with the devices.

Regards,

Scott T
Applications Engineer
National Instruments

[Angelantoni]

Hi all

Thanx for your replies, If I use watchdog for monitoring the PXI how do I generate the pulse, In watchdog configure.vi's expiration action there is an option for trigger, I can see the option of SMB line0, and range of Line0-7 in this. I believe SMB line0 is the trigger output on the front panel of the PXI, Is this correct?.
Just by selecting trigger as SMB line0 will I get a pulse at the front panel? Or is there any thing else I have to do?

Thanx for your replies.
Arun