Network Led on FP1001 module is full bright but no communication

[martien]

Dear all

I am working on an installation with 9 FP1001 modules in an RS485 network. I needed to connect this system to a new device (a Moxa ethernet / RS485 converter) and got it all operating well. I am using 4 wire connections which were already in operation many years. After a few days of succesfull operation, two modules suddenly failed. I did not manage to get them going by power cycling / field point explorer restarts / plugging in an out the network connector etc. What triggers me is that for both modules the network LED is highly bright orange (I would say but the user manual says yellow). This bright LED comes on immediately after restarting the FP1001. I then replaced the two FP1001 modules with two other spare ones and got the network going again.

I am now testing the two modules on a separate test set up which I have up an running with a good working FP1001. Replacing this one with one of the failing ones gives the same problem (bright network LED activity). Is this an indication that the FP1001 are definitely broken (all other LEDs are working OK ? If yes, is there anything in my network which can cause this ? I am afraid of getting more broken FP1001 modules in the next days.

Any help is highly appreciated

Martien

[NPowl]

Hey Martien,

You mention that the two modules suddenly failed - what do you mean by this? Do they not send any data / don't communicate at all? Is there any activity on the STATUS or ACCESS LEDs? I'm assuming that the Power LED is green as normal.

It seems that we've identified that those two modules are definitely the problem if we have swapped various hardware around. 

Is there any chance that the network address on the modules changed somehow, and need resetting?

I'd advise being as careful as possible with the FP modules; they're obviously obselete so there's no chance of replacing them if they break. Is there a reason we're still on these rather than upgrading to a cRIO system?

Cheers,

Nick

[martien]

Dear Nick

Thanks for your reaction. The system I am working on is at a customer site and I am definitely pushing them to upgrade the system for which I indeed recommend also cRIO or any other system using the C-modules, which is our standard praxis for many years already. I agree to be careful with FP1001 units, that's why I try to keep the few spares I have "alive". 

However,this system has not been phased down yet by the customer and has to remain active so therefore my request for more info. Back to this topic:

a) Two units failed at app. the same moment

b) After failure no communication is possible at all. NI-Max can not find the modules, while if I hook up any correct functioning FP1001 module in the same network it works perfectly.

c) The Power Led is on, Access and Status Leds remain off, the Network Led is bright orange and not switching. From the user manual I read that the network led should show traffic by intermittently going on and off which I can also see on all the other modules. I could not find anything in the user manual about the led being on 100% of the time,

d) There was no address change or any reset on the network while this happened. Our software collects the error messages generated and when the 2 failing units broke communications errors were collected in our software, all other units run without any problem and generated no errors at all. 

e) As further info, each FP1001 unit has 4 FP-120 thermocouples blocks and one AI block connected.

Thanks for your reply

Martien

[NPowl]

Hey Martien,

It seems that an unlit STATUS LED indicates there isn't an error, ACCESS LED means that there was no communication with the host computer, and the POWER LED shows that we have correct power. All of this seems to point that the module hasn't detected an error - if the NETWORK LED is bright, it may think it's receiving a large amount of traffic onto the module as the LED gets brighter the more traffic there is.

If they failed at the same moment and we can't recreate it, is there any chance there was a power surge of some sort? 

What happens if we power the modules but don't connect them to any network at all?

Cheers,

Nick

[martien]

Dear Nick

Thanks for your reply.

If the modules are powered and the network connector is taken off, the bright Network Led goes off immediately and immediately on again when the network connector is plugged in.

I am also worried about a power surge or something like that, that's why I wanted to understand if such bright Led could be the indication of a damaged board.

I do now have one extra bit of info. At the time of the failing units, I actually had made a "failure" in the RS485 network. This resulted in a "T" network with at each of the tree legs 120 Ohm resistors on the TX and RX lines. One leg did not contain any modules but was just having the resistors at the end of what I estimate 20 meter of cabling. Despite this incorrect network configuration, the communication with all 9 devices worked well for a day or more (this system is up and running 24x7) until the failure with the 2 modules occurred. I did correct this about two days ago by removing the "empty" leg with its resistors. Until now it is still working OK.

Regards

Martien

[NPowl]

Hey Martien,

Unfortunately I can't find anything regarding a bright network LED that won't quiet on the network, and we don't seem to have a way of performing any reset function on the module; I'm not too sure what we could do. Perhaps someone else may have a better idea of this.

This seems like a time to broach how your customers should move to something a bit more supported if we have started to see hardware fail for unknown reasons - there would be more troubleshooting available and the option for repairs.

BW,

Nick

[martien]

Dear Nick

Thanks for all the attention paid to this topic.

I will try some further test on the faulty units and then dispose of them if I can't get them to work.

Rest assured that I will try to convince the customer to upgrade their systems.

Kindest regards

Martien