Unclear watchdog functionality

[Fedor]

Field point controller FP-2015

NI Max 5.5

Windows 7 host with Labview 2012

FP <-> Labview host connection: Ethernet

I would like remote FP system to go into watchdog configuration if host PC or Labview application on the host stops functioning for any reason.

I switched Network watchdog configuration to "Enable for Bank" with default time-out of 5000ms for the remote FP-2015 system. I also enabled watchdog on respective FP devices and channels.

1. When I pull Ethernet plug, the modules go into watchdog-specified state after 5 seconds

2. When I stop or close Labview host program  that communicates with FP system, watchdog does not trigger. 

According to this responce, it should go into watchdog in condition 2, but it does not. The NI MAX/Field point documentation itself  is unclear on what constitutes communication failure.

Also, is it possible to have some sort of "keep alive" logic on FP system, where it would require host to send keep alive signals to FP system  every now and then which otherwise go into safe state?

Please advise.

[RavensFan]

Could you have something else going on that is maintaining a communication link with the controller?  Such as if you have MAX open and monitoring the channels that way?

You could certainly build a watchdog loop into your application that keeps track of how much time has passed since it received its last "whack" message.  If the limit has been exceeded, then it communicates with the rest of the code to shutdown or do whatever you need it to do to reset outputs.

[Fedor]

MAX was closed during test. The host and FP are linked with a single Ethernet  crossover cable, so there's nothing else but the host that is present on this network. Do you mean that FP-2015  indeed supposed to trigger watchdog in situation (2) in my original post? I wonder if MAX or NI FP driver are still active in the background. How to disable it?

Concerning watchdog loop in application - the situation I describe is when application or host become unresponsive/dead as a whole. Just to clarify, FP-2015 is used as a "dumb" Ethernet controller and there's  no custom RT code deployed to FP.

[SkyWalka]

Is this the documentation you were referring to? http://www.ni.com/white-paper/3347/en/

It discusses how the Watchdog works and what can trigger it.

[Fedor]

Yes, I've look through it before, and it states that:

FieldPoint Ethernet Network Modules
When you start the FieldPoint server (such as running FP Open.vi, opening FieldPoint Explorer, or accessing the OPC server), the server requests a subscription from the network module for each Ethernet item in its .iak file. The network module maintains a count of all the subscriptions granted to a FieldPoint server(s). ... The watchdog timer is then reset each time the network module receives the heartbeat. If the watchdog timeout period expires before the network module receives the heartbeat from a FieldPoint server, the watchdog deactivates the subscriptions for that server. If the subscription count falls to '0', the network module reverts to the user-defined watchdog settings.

When you close a FieldPoint server, you deactivate the subscriptions for that server. If that server was the only one subscribing to data items from the network module, the subscription count falls to '0' and the network module reverts immediately to the user-defined watchdog settings.

...but when I stop and close LabVIEW App, LabVIEW, NI MAX, everything on the host, the FP module does not trigger watchdog, in contradiction with the above.

[RavensFan]

---

@Fedor wrote:

 Do you mean that FP-2015  indeed supposed to trigger watchdog in situation (2) in my original post? I wonder if MAX or NI FP driver are still active in the background. How to disable it?

I agree with you that it soudns like it should have triggered the watchdog.  I looked up the instructions for both the 1601 and the 2015 modules to see if there was anything different about their watchdog behavior.  It seemed like the two instruction sheets were identical in their descriptions.

I don't know if Max would have or even should have still had something running in the background after you closed it.  I don't think it should.  I just figured if you did have MAX open, it might have been the thing keeping the watchdog ticking.

Concerning watchdog loop in application - the situation I describe is when application or host become unresponsive/dead as a whole. Just to clarify, FP-2015 is used as a "dumb" Ethernet controller and there's  no custom RT code deployed to FP.

---

The FP-2015 has the power to run the custom RT code.  I would take advantage of it.  I think it would be more reliable.