Profibus DP - General Information

Profibus DP in the DeltaV System

The DeltaV Profibus DP card conforms to the Profibus specification as an interface to a control application such as the DeltaV system and provides some diagnostic information on slave devices. There is one port on the DeltaV Profibus DP card.

In order to use Profibus DP with a DeltaV system, Profibus must be enabled as a System Preference. (Start → DeltaV Engineering → System Preferences)

Use DeltaV Explorer to:

Refer to the DeltaV Explorer online help for detailed information on adding and editing Device Definitions and configuring Profibus devices.

Important

If one or more bits of a Profibus DP signal output tag are unused (masked) and sent to a slave device, the masked portion of the signal outputs may be driven to unexpected values. Also, if a control module that is writing to an output of a Profibus DP slave device is deleted in the DeltaV Explorer, the module's signal value persists until the device is deleted and the card downloaded. Refer to KBA NA-0900-0054 for more information on these scenarios.

Tips

  • A Profibus DP compliant connector is used for connecting Profibus DP devices onto the bus. The connector has one IN wiring connection and one OUT wiring connection. When a Profibus connector is set to TERMINATION ON, the OUT wiring is no longer connected to the bus. Thus the termination can only be used on the last connector on a segment connecting several Profibus devices.

  • When initially commissioning a Profibus segment, the DeltaV Diagnostics indication of Not Communicating with Device is often just due to no signals being configured for the device. To determine if the device is communicating, look at the Station Non-Existent indication in the device information in DeltaV Diagnostics. To view this window, right click the device in DeltaV Diagnostics, select the General Tab → Display Device Information.

  • After changing address switches on a device, power cycle the device before configuring and downloading.

  • When a device address/slot address is changed, the port and all control modules using that device must be downloaded.

  • When changing port parameters and performing a download, the Profibus DP I/O card will re-initialize and all motors might stop dependent on the previously configured failsafe conditions for the device.

  • Careful attention must be used when selecting the Profibus DP I/O card's port configuration for Action in event of CTLR failure. This selection will determine whether, ALL devices will RESET, or hold LUV when a controller has a power failure and there is no redundant controller (or a switchover fails).

  • If a device is continually going offline for a short amount of time, noise being one case, the retry count must be increased from 4 to between 10 and 20. Open the port's Properties dialog and select the Advanced tab.

  • Device address clashes (two devices at the same address on the same segment) can have two possible indications in DeltaV Diagnostics (right click and select Display Device Information):
    • DeltaV can indicate that the devices (stations) are non-existent.
    • The Device State will be shown as Offline if the watchdog is set.

    If there is a device address clash, the outputs will either go to failsafe or hold last value depending on the device. For example, the STAHL outputs will go to failsafe conditions with the red LED indicator flashing for the output I/O module(s), while the ET200S outputs will hold their last value.

    Note

    There is no local indication on the main module that there is a communications problem.

  • The module selection for the SLOT is used to set up the input and output word requirements. Each SIGNAL is used for either input or output data. Often the data word will be accessed through an external reference parameter. By using the Boolean Fan type blocks, bits inside the SIGNAL word may be accessed.

  • If the Profibus card should require a flash update, field devices or converters on the Profibus cable may need to be power cycled to allow proper communications to resume. Disconnecting the Profibus cable from the termination block prior to flashing the Profibus card should prevent this from happening.

  • If an error relating to input or output byte length is indicated when first trying to add a new Profibus device to the port on a Profibus card, be sure that Modular_Station = 1 is shown in the GSD. If this parameter is set equal to "0", an error can occur when attempting to add the device to the port.

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