Profibus diagnostic signals

Hi,

 

I have noticed that Profibus signal objects have a property "Use diagnostic channel". What does this exactly do? It allows the instrument to set the status of the signal which I read from the port?

How do I know whether my device supports these diagnostic channels? How do I know which channel number to use?

Thank you,

 

Istvan

  • Istvan,

    Yours is a very good question, as there is no information on this in standard documentation of DeltaV.  I'm not 100% sure, but it appears that when using an IO type device, Profibus knows how to handle module and channel level diagnostics.  So if the signal configured is for a module channel, you can select this option and specify the channel number.  DeltaV will set the Channel Bad if the device reports a fault on that channel.

    I found an example where the AI block in DeltaV, configured to a signal that has this diagnostic enabled, shows a BAD status (red X) in Control Studio On Line.  

    The details of the fault can be seen in DeltaV diagnostics.  Navigate to the Profibus device under the controller, IO, card, port, and right click, Display Device Diagnostics. A dialog appears with 8 or ten Tabs. The channel fault will appear in the tab for the channels.  

    From what I can tell, this is avialable on devices that are IO type nodes, with IO modules that have channels on them.  I don't know if it is possible to use this feature on other types of devices. It would be nice that if a device has a "diagnostic channel", then you could use this to assign GOOD/BAD Status to any signal where such a diagnostic is applicable.  I assume such a channel would be defined somehow in the GSD of the device, but I dont' know what that might look like.

    This diagnostic information is not part of the polled data from the device.  When a diagnostic condition occurs, the Host master is informed that diagnostics are available, and on the next scan, polls for this data and parses it.  The first 6 bytes are standard infomration, and are displayed in this diagnostic dialog for all devices.  Additional information is device specific, and in the case of the IO products, dependent on the physical location of modules installed.  

    DeltaV v11 allows you to poll the DIagnostic array of the profibus device and from there, you can derive the information contained, provided you know the data structure.  The GSD file needs to provide this structure for the host system to be able to use it.

    SO in summary, if you have an IO type proibus device (I.S.1 from Stahl), you can configure diagnostic status onto the signals to monitor individual wiring health of connected field devices.  Note this is not health of actual instruments connected.  DeltaV diagnostics will provide technician more details of the source of the issue.

    Hopefully, someone can contribute some additional information on this subject.

    Andre Dicaire

  • In reply to Andre Dicaire:

    hello,

    I´ve attached a link for the explanation of the ET200S modules diagnostics. (cache.automation.siemens.com/.../Diagnose_ET200S_e.pdf)

    Niklas Flykt 

    Klinkmann Oy

    Key Account Manager safety products

    nikfly@gmail.com