Fieldbus devices are field instruments, such as transmitters and valves, with processors that monitor device performance and state. Fieldbus devices use a digital, rather than analog, connection to a host system such as the DeltaV system. Function blocks reside in the fieldbus devices and enable the devices to execute control in the field. Fieldbus devices notify the control system of standard operating parameters and are self-diagnosing and capable of reporting device problems such as instrument out of calibration to the control system.
Each fieldbus device must have a unique physical device tag and a corresponding network address. The device tag is assigned to the device when it is commissioned and (for most device states), the device retains the tag in its memory when it is disconnected. The device does not retain the tag when the device is made Spare. When the device is made Spare, the tag information is lost. The network address is the current address that the fieldbus is using for the device. The Fieldbus Foundation uses addresses in the range 0-255. Group addresses and DLLs use addresses 0 - 15, commissioned devices use addresses 20-35, standby devices use addresses 232-247, and offline and spare devices use addresses 248-251.
Fieldbus supports four device classes:
Note Link Master devices should always be Commissioned. Unpredictable behavior could occur if a Link Master capable device is in Standby or Offline and the Primary Link Master device fails. Any temporary device should only be connected to the fieldbus as a Basic device.
For more information, refer to the Commissioning and Decommissioning Fieldbus Devices topic.
A Device Description is similar to a driver for the device. For fieldbus devices, the Device Description includes the calibration procedures, parameter procedures, and other information required by the control system to communicate with the fieldbus device. Standard Device Descriptions are provided by the Fieldbus Foundation and optional, incremental Device Descriptions are provided by the device manufacturer. Device Descriptions are written in the Device Description Language (DDL) and the host system such as the DeltaV system uses library functions called Device Descriptions Services to read the Device Descriptions. Device Description technology enables interoperability among fieldbus devices. Interoperability, a key benefit of fieldbus technology, is the ability of a host system to operate multiple devices, independent of manufacturer, on the same fieldbus segment without loss of minimum functionality.
The DeltaV system supports a number of fieldbus devices from different manufacturers. The device description files necessary to support these devices are included in the DeltaV install image. If a fieldbus device is not included in the DeltaV install image, you must install the device description for that device. The device description is specific to the device type and revision. Download the device description files from www.easydeltav.com The device description files must include a file with an .fhx extension to work with the DeltaV system. You can download the device description files to a disk, CD, or directory on your system and then use the DeltaV Explorer to add the device type to the DeltaV Explorer library. Install the device description files on the ProfessionalPLUS workstation and the DeltaV system synchronizes the device descriptions on the other workstations. Refer to DeltaV Explorer help for information on how to use the Add Device Type command.
Device Descriptions can also include a set of processing routines called Methods. Methods provide a way to access and manipulate parameters within a device. For example a DD for a Valve Controller might include methods for automatically calibrating valve travel, manually calibrating travel, restarting a device, and calibrating the internal pressure sensor information for display. Methods are available from the device's context menu in DeltaV Explorer.
You can provide access to device methods from DeltaV Operate pictures using scripting that call the AMSMenu application included with DeltaV software. The AMSMenu application opens a menu that contains device methods. The command line for the AMSMenu application has two forms which take different command line parameters:
AMSMenu <dev tag> -bi <blk index>
AMSMenu -n <dev tag> -m <mfg id> -t <dev type id> -r <rev num> -i <phys dev id> -bt <blk tag> -bi <blk index>
where
dev tag is the tagname of the field device in the database,
blk index is the block or object index of the device's Resource or Transducer block listed in DeltaV Explorer,
mfg id is the identifier code for the device manufacturer,
dev type id is the identifier code for the device type,
rev num is the device's revision number,
phys dev id is the unique identifier for this device type,
blk tag is the tagname of the resource or transducer block of the device,
blk index is DeltaV Explorer object index for the device's Transducer or Resource block.
Note: The mfg id and the dev type id must be the hexadecimal values.
With the first form, the AMSMenu application connects to the DeltaV database to get the manufacturer, type, and revision of the device, then passes this information to the same AMS Device Manager interface that DeltaV Explorer uses.
In the second form, the command line provides all the device information so the AMSMenu application does not connect to the DeltaV database and is therefore faster.
For example, if your configuration includes a device named FY-101 that has the following characteristics:
The following script opens a menu when the object the script is attached to is clicked:
Private Sub Rect1_Click()
frsruntask "AMSMenu", "-n FY-101 -m 5100 -t 5900 -r 7 " _
& "-i 0051000100FisherDVC0112461319931 -bt TRANSDUCER -bi
450"
End Sub
The menu that it opens is:
These are the same methods that appear if you right click the device's Transducer block in DeltaV Explorer.
See Working with Other Applications in the DeltaV Operate manual for more information.
When the H1 fieldbus cards are plugged into the I/O carrier, the fieldbus devices are connected to the H1 cards' terminal block, the Device Descriptions loaded, the H1 card automatically detects the fieldbus devices, recognizes the device types, and makes this information available to the DeltaV system.
Note The DeltaV system autosenses the H1 cards.
As with other cards and devices, you can add H1 cards and fieldbus devices as placeholders in the DeltaV Explorer. A placeholder device matches the manufacturer and model of a device that has not been connected and holds the device tag and address. When you are ready to commission the device, move it to Standby, and drag the device to the placeholder. The device connects to the segment with the device tag and address that was specified for the placeholder.
Commissioning and decommissioning fieldbus devices is done in the DeltaV Explorer and involves moving the devices through several device states. The online help for the DeltaV Explorer explains how to commission and decommission fieldbus devices. Fieldbus devices have five stable states in the DeltaV system:
Commissioned - For a fieldbus device that is at its assigned address. To move a commissioned device to the Off-line or Spare state, you first decommission the device.
Caution It is recommended that if you intend to keep a fieldbus device in the Off-line or Spare states (decommissioned) for any length of time, you remove the device from the segment. A decommissioned fieldbus device is given a temporary address and failure to remove it from the segment could prevent normal commissioning on the segment.
Off-line - For a fieldbus device that you want to disconnect for maintenance and then return to the segment at the same address. For example, you would take a device offline to recalibrate it. If an off-line device is reconnected, it automatically uses a standby address. You must commission the standby device by dragging and dropping it onto the appropriate placeholder. After the device is commissioned, download the device in order to make it function as it did prior to being decommissioned.
Spare - For a fieldbus device that you want to disconnect and no longer use in your DeltaV system. Each device has a device tag that designates the role the device performs in the DeltaV system. If you decide that you no longer want to use the device, you should clear its tag. To clear the tag, make the device spare. A spare device is part of your inventory of spare devices, not an instrument with a specific purpose. If, at some time, you decide to put a spare device back into service, the system moves it to Standby automatically when you attach the device to the segment.
Standby - A safety feature for fieldbus devices. The device is moved to a standby address until it is commissioned. A device comes to standby from the Off-line and Spare states.
Mismatch - The fieldbus device was commissioned on another control system and then connected to a DeltaV system. When the H1 card finds a device in the assigned address range that has not been commissioned for this particular segment, it designates it as a mismatched device. A mismatch device can be commissioned.
Device Class Mismatch - The attached field device is not the same class for which the device was commissioned.
Schedule Download Failed - The LAS Schedule could not be downloaded to this field device.
The following figure shows state transitions in fieldbus devices.
State Transitions
Fieldbus devices can also go through the following transitional states:
Comm Initializing - The H1 card is establishing communications with the field device.
Unrecognized - The field device has not been commissioned at this address.
Unknown - The field device is transitioning between states.
Typically, a device will be in one of the above states for only a few seconds. If it remains in one of these states it indicates a problem. Additionally, if a device goes into the Comm Fail state it indicates that the device is communicating on the bus (it is in the live list) but communications between the H1 card and the device is currently disrupted.
If a device remains in the Comm Initializing or Comm Fail state, cycle the device power. If a device remains in the Unrecognized state, it either has not been commissioned or has been attached to the wrong segment. If a device is in the Schedule Download Failure state, then the segment currently does not have a functional backup LAS. If a device shows a Device Class Mismatch, there is something wrong with the device.
The DeltaV Explorer, Control Studio, and Diagnostics programs as well as the H1 card itself provide a great deal of diagnostic information on fieldbus devices.
H1 Fieldbus Card
Communication information between the card and fieldbus devices is available from a visual inspection of the H1 card. The bottom two LEDs on the H1 card reflect communication between the port and fieldbus devices on that port. A blinking yellow LED indicates that the port is communicating with fieldbus devices but either a communication problem exists with an attached fieldbus device or no function blocks are configured on the segment. If the LED is off, either the port is disabled or the H1 card is not communicating with any fieldbus devices on the port. Use the DeltaV Explorer to enable and download the port and Control Studio to create and download configuration. A solid yellow LED indicates good communication between the port and devices on that port and at least one function block is configured on the segment.
DeltaV Explorer
Indicators in the DeltaV Explorer tell you if an H1 port or a fieldbus device needs to be downloaded or commissioned.
on an H1 port or device means that the port or device needs to be downloaded. Select the port or device, click the
right mouse button, and then select Download to open a dialog box that lists the fieldbus configuration information to be downloaded.
on a device means that the device needs to be commissioned. To commission the device, select it from the
Decommissioned device list and drag it to either the port or device placeholder.Control Studio
Use Control Studio in online mode to diagnose problems with modules running in fieldbus devices. You must assign and download a module before viewing it in online mode.
Caution Any online changes affect your process because the changes are made to downloaded modules in the controller. Use extreme care when changing values or stopping the execution of an algorithm.
Diagnostics
Use DeltaV Diagnostics to perform the following tasks:
Open DeltaV Diagnostics and click View | Details or View | Compare to quickly see the device state. If the device is not commissioned, open the DeltaV Explorer and commission the device. Then, download the port and the device. If the device is commissioned, check integrity on the port and then check port and device communication statistics.
Port Integrity
Typically, integrity problems originate below the node and then rise to the node level. Integrity problems are indicated by the 
overlay. Start by looking for a controller with the 
overlay and, if found, expand the controller hierarchy until you find the
root cause of the problem. If a fieldbus card has an integrity problem, expand the card to see which port has the problem. Select each port and look at the port's status. Possible port status values
are:
Port Communication Statistics
The Port Statistics command provides a broad view of communication activity on the port. Click the right mouse button on the port and then click Port Statistics. In the Port Statistics dialog look for the following:
Note If any of the port statistics and communication statistics are continually increasing, a potential communications problem could exist on this port. To isolate the problem, investigate the communication statistics on each fieldbus device. Refer to the following section for information.
Next, look at detailed port statistics. Click the right mouse button on the port and then click Display Port Detail Statistics. In the Detailed Port Statistics dialog, look for the following:
Tip Clicking the Reset Stats button resets all values to 0 and makes it easier to read the statistics.
Device Communication Statistics
Finally, look at communication statistics for each device. Click the right mouse button on each device, click Display Communication Statistics, and look for the following:
Fieldbus devices can be configured to detect and report specific device alert conditions directly to the DeltaV system. These conditions can range from potential problems (such as hardware failures within the device, loop problems, and misconfigured parameters) to proactive reporting of upcoming maintenance needed. To view Foundation Fieldbus device conditions in DeltaV Explorer, right-click the device and select Status/Conditions.
Optionally, device alarms can be enabled on a Fieldbus device. When a device detects a condition, it will generate an alarm, in addition to setting the appropriate condition on the status or conditions screen. The alarm is reported in the Event Chronicle, is displayed in alarm summaries, and may be displayed in the DeltaV Operate alarm banner, depending on user configuration (Series 2 H1 card required). A standard device faceplate shows the active alarms for a fieldbus device. The detail button on the faceplate accesses the same screen as the Status/Conditions selection in the DeltaV Explorer.
Device condition functionality is dependent on the device. Foundation Fieldbus devices support either standard Foundation Fieldbus alerts or PlantWeb alerts.
Standard Foundation Fieldbus alerts - Devices report alerts in a single alarm: abnormal. This alarm is based on the standard Block Alarm definition.
PlantWeb alerts - Devices report alerts in one of three alarms: failed, maintenance and advisory. The device alerts have been organized into one of these alarms based on the importance of the alert condition to the health of the device.
With the DeltaV system, all Foundation Fieldbus devices also have a communications failure alarm. This alarm is generated when the DeltaV software recognizes that a device is no longer communicating on the H1 segment.
Fieldbus devices that support PlantWeb alerts also allow you to suppress conditions from the Status/Conditions screen. Suppression from the Status/Conditions screen prevents the device from reporting the condition to the DeltaV system. It is also possible to prevent reported alarm conditions from appearing in the alarm banner and alarm list. This type of alarm suppression is described in the Suppressing Device Alarms topic.
You can suppress device alarms from several places in the DeltaV system:
Because alarms contain multiple conditions, suppressions at the alarm category level will always override suppressions at the condition level.
Example:
A fieldbus device reports that it is due to be calibrated. The Calibration Due condition appears as a Maintenance alarm in the Status/Conditions dialog, the DeltaV alarm banner, and Event Chronicle. Because regular service is scheduled for the following week, the user might choose to suppress all Maintenance alarms from that device using the Details faceplate. Alternatively, the user could choose to suppress only the Calibration Due condition from appearing in the alarm banner and the Event Chronicle by checking the box above the condition in the Status/Conditions dialog for that device. In both cases, the Status/Conditions dialog continues to display the condition as active.