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Frequently Asked Questions

Unable to load DNP3CLRAdapter or one of its dependencies

.NET does not provide useful error messages when an assembly can't find a native dependency. The .NET bindings depend on the Visual C++ Runtime library for the version of Visual Studio you used to build them.

These packages can be found from Microsoft by searching for "Visual Studio C++ Runtime" in your favorite search engine.

You might also see this error because CLRAdapter can't find OpenSSL (libcrypto.dll / libssl.dll) if your bindings didn't have these linked statically. The solution is to make sure OpenSSL is installed in the correct system location.

Note that older versions of OpenSSL (< 1.1.0) have DLLs with different names (namely libeay32.dll and ssleay32.dll). These are NOT suitable for the 3.0 version of OpenDNP3. You need OpenSSL 1.1.1 or higher.

My master and outstation don't communicate

The most common mistake when configuring a master to talk to an outstation is neglecting to set the correct addresses. DNP3 was originally designed to communicate on a shared serial bus, so components ignore messages sent to addresses other than their own. Outstations expect to receive messages from a particular master, and will only respond to that master if both the source and destination link-layer addresses are set correctly.

Master or Outstation doesn't detect an ethernet cable being unplugged

There is no way through the standard socket API to detect this, other than trying to write data to the socket. This means that if master or outstation sessions are quiescent (meaning that they don't write data periodically), you should be using the link-layer keep-alive feature to ensure that dead/hung connections are appropriately detected.