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:
Hi Andre,
Thanks for your input. I indeed found a KBA which, although a bit sketchy, describes how the Siemens ET200S should be configured to use diagnostics: AUS1-131-000601153757. This is a remote IO module.
I tried it and I have managed to get some BAD status on some of my signals. I will need to investigate that further, though.
In reply to István Orbán:
Reviewed the KBA. It does not explain how things work, but if you read between the lines, you see that the device must be configured to provide the diagnostics. I am not familiar with the ET200, but I expect that the device and/or each module has some configuration parameters that show up in DeltaV Explorer. Configuring these parameters as indicated enables the channel diagnostics. The DeltaV signal can then be configured to monitor the specified channel and set status to BAD on a fault.
It does not explain where to read the details of the channel or module faults, which is in Diagnostics Explorer. navigate to the device, right click and select the "display Device informaiton", which pops up a dialog with an assortment of Tabs, one of which is Channel information.
I may be mislabeling some of these menu and tab items, so if you are running through this, please correct my information and let us know how this is working.
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
In reply to Niklas Flykt:
The DeltaV M-series Profibus DP Interface Card (master)
cyclically reads the input information from the slaves and
cyclically writes the output information to the slaves. In
addition to cyclic user data transmission, Profibus DP
provides powerful functions for diagnostics and configuration.
The extensive diagnostic functions of Profibus DP enable
fast location of faults. The diagnostic messages are
transmitted over the bus and collected at the master.
These messages are divided into the following three levels:
Station-related diagnostics.
These messages concern the general operational status of the whole device
(i.e., over temperature or low voltage).
Module-related diagnostics.
These messages indicate that a fault is present in a specific I/O range (i.e.,
8-bit output module) of a station.
Channel-related diagnostics.
These messages indicate an error at an individual input/output bit (i.e., short
circuit on output 7)
video tutorial on Profibus: www.youtube.com/watch