Troubleshooting the OPC Classic DA Collector

Troubleshooting Tips

When reviewing the OPC Classic DA collector log file, or the log messages from Event Viewer:
  • If you notice a message that states that Historian could not create the buffer files, then the issue is most likely that you do not have enough free space available for the buffer files.
  • If you notice the OPC Classic DA collector connection attempt, a COM initialization attempt, and then a shutdown, the cause of the error is most likely that the collector is trying to start before the OPC server fully starts.
  • If you look at the log files and you do not see anything special, aside from a startup attempt and a shutdown message, then begin by assuming that the OPC server is not fully starting. If the workaround for that issue does not appear to work, try adjusting the buffer size.

Issue: The Collector Fails to Start

Possible Causes:
  • There is not enough free space for the collector to create its buffer files on startup.
  • Historian is trying to run the OPC Collector before the OPC Server fully starts.
Try the workarounds in the following sections.

Issue: Not Enough Space for Buffer Files

Workaround: Try one of the following options:
  • Free up the disk space.
  • Move the buffer files to a different location.
  • Change the buffer size by adding a DWORD MinimumDiskFreeBufferSize in the registry under HKEY_LOCAL_MACHINE\SOFTWARE\Intellution, Inc.\iHistorian\Services\OPCCollector\<collector interface name>. We recommend setting it to 10 or 20 MB. After you save your changes, restart your machine.

Issue: The Collector does not Connect to the Historian Server

Workaround: Check the Logfiles folder on the collector machine. If the log file specifies "could not create buffer files", repeat the workaround in the previous issue.

Issue: The Collector Tries to Start Before the OPC Server Starts

Workaround: Specify a time delay for the collector to start. To do so, add a DWORD named MachineUpTimeDelay in the registry under HKEY_LOCAL_MACHINE\SOFTWARE\Intellution, Inc.\iHistorian\Services\OPCCollector\<collector interface name>. We recommend that you set its value to 120 seconds first, and restart the collector. If the problem still exists, try increasing the value slightly until the issue is resolved.

Issue: The Collector Becomes Unresponsive After the First Polled Read

Workaround: If the polled reads take more than a few seconds to start:
  1. Create a DWORD named OPCFirstReadMode in the registry under HKEY_LOCAL_MACHINE\SOFTWARE\Intellution, Inc.\iHistorian\Services\OPCCollector\<collector interface name>.
  2. Provide one of the following values:
    • 1: Use this value if you want the collector to perform the faster OPC_DS_CACHE read on the first poll.
    • 2: Use this value if you want the collector to perform the slower OPC_ DS_DEVICE read.
  3. Restart the collector.

Validating Items Before Adding to Polled Collection Group

To validate items before adding them to the polled collection groups from the collector, create a DWORD named OPCValidateBeforeAdd in the registry under HKEY_LOCAL_MACHINE\SOFTWARE\Intellution, Inc.\iHistorian\Services\OPCCollector\<collector interface name>, and set the value to 1.

Issues with Browsing for Tags

Workaround:
  • Some OPC servers do not support data blocks with a length greater than 1. These servers display only the first item in an array instead of showing all of them. For example, an OPC server may contain 3000 analog values from datablock:1 to datablock:3000, but only datablock:1 is displayed.
  • If you want to archive data from poll records of a length greater than 1, we recommend that you use the Excel Add-In for Historian to configure a large block of tags (including the missing items), and then add the tags.
  • If you are unable to browse items containing a forward slash ( / ) in your OPC server, you may have to change the default separator in the collector configuration. To do so, modify the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Intellution, Inc\iHistorian\Services\OPCCollector\<collector interface name>\OPCBrowseTreeSep key, and change the string value to a character not available in your OPC server item IDs. Typical values include |, !, or &. Create this key if it does not exist.
  • If you are cannot browse readable items in your OPC server, you may need to change the browse access mask used by the collector. To do so, modify the registry key [HKEY_LOCAL_MACHINE\SOFTWARE\Intellution, Inc.\iHistorian\Services\OPCCollector\<collector interface name>, and add the DWORD key "OPCBrowseAccessRightsMask"=dword:00000003. Valid values are 0, 1, 2, 3 with 1 being the default. Use 0 or 3 if you are unable to browse readable items. Creating or changing the value takes effect on the next browse attempt and does not require a collector restart.
  • Some items such as unsupported data types and user-defined items in simulation servers may not be returned when you browse for tags. However, sometimes, even the items that do not appear in the search results can be added using the Add Tag Manually button.
  • If you connect the collector to a Kepware Redundancy Master with both primary and secondary servers using Industrial Gateway Server (IGS) that share the same channel, device, and tags:
    • After creating a tag in Historian, if you modify the tag’s source address, the tag will be considered invalid until the collector is restarted; data is not updated for the tag and the quality is not set to bad.
    • Always restart the Redundancy Master service before restarting the collector.
    • If you add IGS tags to Historian, you cannot delete them in IGS. If you try to do so, the following error message appears in IGS: Rejecting attempt to delete reference object.

      To avoid this error, first delete the tags in Historian, and then delete the device in IGS.

    • If you cannot browse IGS for tags, restart the collector.