Using FieldPoint Logos Server with the LabVIEW DSC Module

This document shows how to access FieldPoint distributed I/O from the LabVIEW Datalogging and Supervisory Control (DSC) module. There are three communication protocols a user can choose from in order to connect these two products: OPC, Logos, and IAK protocols. This document only describes the Logos method, which is the preferred way for FieldPoint Ethernet modules. For overall comparison of all these methods, refer to the following link: LabVIEW DSC Module to FieldPoint Connectivity .

The major benefits of using Logos are:

• Ability to change channel ranges programmatically
• Direct connectivity to hardware--no intermediate process, such as OPCFieldPoint
• No need to use and later deploy the IAK configuration file

Major disadvantages are:

• Only supports Ethernet network modules
• Not an industry standard
• A little bit more complicated channel generation

Device Configuration

The very first step in the setup is to configure the FieldPoint Ethernet devices. At the end of this step you should be able to access your FieldPoint devices from FieldPoint Explorer. If you have already done so, proceed to the next step; otherwise, refer to the document below. Note that the FieldPoint configuration file (.iak) is not required by the Logos server. You can run the configuration on one computer and then access it from the DSC module on another computer, without distributing the .iak file.

See Also:
FieldPoint Ethernet Configuration

Tag Configuration

Once you are able to connect and monitor your channels from FieldPoint Explorer, you are ready to configure your LabVIEW DSC module tags.

1. Start LabVIEW and open a new VI.

2. Launch the Tag Configuration Editor by selecting Tools»Datalogging & Supervisory Control»Configure Tags.

3. Create a new SCF file. Select File»New. In LabVIEW 6.1, you'll get a File Information window. Accept the default values by clicking OK.

4. Launch the automatic tag generation by selecting Edit»Configuration Wizard.

5. The Configuration Wizard window should appear. Locate the Registered Computers entry in the left pane and expand the hierarchy. You should see all FieldPoint Ethernet modules running on your subnet. If the network module is not on the same subnet, you have to register it manually. Pop up on the Registered Computer entry and select Register Computer. Enter the Ethernet module IP address in the Computer name box of the new window and click OK.


6. Note that there are a few entries underneath the registered computer name. Here is an example:


Select the channels you would like to add to your DSC configuration and click the Add Item(s) button. Read the following tips before you do so:

Tips:

• Note that this unit has two major nodes: FP and LV - right underneath the IP address. All FP-1600 modules have an FP entry only; all FP-2000 modules define a LV process in addition to FP. Apparently this is an FP-2000 module that we have accessed, since there are both FP and LV processes running. The FP process exposes the I/O modules, while the LV exposes the user defined tags (with Publish Data.vi).
• If you further expand the FP entry, you will find three types of entries. The first entry is always the network module entry. In the configuration above, the network module is apparently FP-2000, while on the picture below it is FP-1600. The second set of entries represent the I/O bank. There was one FP-CTR-500 module in the above configuration (1CTR) and one FP-TC-120 module in the configuration below (1TC). The leading number in the abbreviated name represents the module-relative position in the bank. Finally, the third entry represents the control tags. You can learn more about the control tags from the Using Advanced DataSocket Commands with FieldPoint Ethernet Network Modules Developer Zone document.
• Primarily, users use the I/O modules. If you expand an I/O module entry, you will get a list of channels. Note that these entries can also be expanded. For example on the picture below, the thermocouple module (1TC) channel 0 is further expanded.
• Note that using direct Logos protocol gives you access to items that are otherwise hidden. This is one of the major advantages of using Logos. You gain control over configuration items and can make configuration changes during run-time. Note that on the other hand it makes the online configuration a bit cumbersome, since adding just the channel 00 also adds all items underneath. In our case below, that is a total of three items. You have to manually delete the two extra channels and just keep the 00 channel.

7. Highlight all unwanted channels and click Remote Item(s).


8. Click OK after you are done with the channel selection. Note that the tags are being auto-generated in the Tag Configuration Editor from the selected FieldPoint channels.


8. Save the configuration (File»Save). Accept the default values for the SCF Logging Path window that appears after you save the file.

9. Now examine the tag attributes. Double-click on a tag to edit the attributes. You will get a tag configuration window with five tabs: General, Connection, Operations, Scaling and Alarms. Press <Ctrl-H> on your keyboard to open the context help window. Move your mouse over the item in question to get the help. Here are a few items that deserve extra attention. See the context help for details.

Operations»Update Deadband (% of range)
Operations»Log Deadband (% of range)
Scaling»Full and Zero Scales

Connection»I/O Group»Edit... settings are unused for Logos protocol.

Tips:

• All deadbands are a percentage of the range entered on the Scaling tab. If your tag values are only updated rarely or not at all, consider lowering the deadbands. Note that the default value is 1%. If you are reading temperatures and the tag range in the Scaling tab is 0 - 4000, then 1% corresponds to 40. Unless the temperature changes more than 40 degrees, the tag values are discarded. Zero deadband is acceptable, but it means the system will be busy with every single update. This might increase your system CPU usage.
• You can predefine the default values that are used for new tags by selecting Configure»Default Parameters.
• If you plan to make a lot of changes to the existing channels, you might find useful to make the changes in Excel. You can export the channel configuration to a spreadsheet file (File»Export...), load it in Excel, make the changes (keep the original spreadsheet format) and import the channels back to EMPTY scf file. (File»Import...)

  Tag Monitoring
  

An easy way to verify that the engine can successfully connect to your device is to use the Tag Monitor utility.
1. Start the Tag Engine by selecting Tools»Launch Engine in the Tag Configuration Editor.

2. Watch for the Tag Engine icon in the task bar tray. A small green triangle should appear on the Tag Engine icon (). This signals that the engine is running. The six-dot icon should also display three green lights (). This icon represents the DSC background services, such as Citadel historical database. In older versions of the LabVIEW DSC module, the services were represented by a light house icon (). In some cases, you won't have the icon in the tray at all, which does not necessary mean the services are not running. Please refer to the document linked below this section for more information, if you run into some issues.


3. Launch the Tag Monitor by selecting Tools»Monitor Tags in the Tag Configuration Editor.

4. In the Tag Monitor window expand the My Computer entry in the tree view. Expand the LabVIEW entry underneath.

5. Add a tag to your view by popping up on the tag and choosing Add.

Tip: You can select and add a range of tags. Highlight the first tag, press the <Shift> key on your keyboard, and highlight the last tag in the range. Pop up on the selection and choose Add.


The right pane of the Tag Monitor displays the value, timestamp, and quality of the selected tags.

6. Save the current view to a Tag Monitor configuration file (*.tmd), by selecting File»Save.

Tip: In the LabVIEW DSC module version 6.1, you can invoke the Tag Monitor programmatically with the Start Tag Monitor.vi. This VI is located in the Tags sub palette and expects a Tag Monitor configuration file name.
The easiest way to create a new user interface control associated with a tag is to use the HMI Wizard.
1. Open a new VI, if it is not open.

2. Create a numeric indicator on the front panel.

3. Pop up on the indicator and select HMI Wizard from the menu.


4. In the HMI Wizard select a tag name from the list box.


5. Click OK to return to the front panel. At this point the wizard generates a code on the block diagram.

6. Start the VI.


7. Check the diagram. It should look similar to this diagram.


The minimum elements that the diagram should contain are:

• An engine loop - this piece of code starts the engine and keeps the VI running, until the engine stops.
• An indicator terminal - this is just the front panel indicator representation on the diagram.
• DataSocket URL Frame (6.1 version only) - the frame associates the indicator with the selected tag; refer to the link below for more information on this piece of code.

  See Also:
  Code Generated by HMI G Wizard - What is it Good For and Do I Need It?
  

Related Links:
Using FieldPoint OPC Server with the LabVIEW DSC Module

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