Optional OPC Client Debug Tracing

The OPC Client includes the ability to enable tracing in order to help diagnose communication problems between the OPC Client and OPC Server. Tracing is managed by a number of parameters and device diagnostic points. By default, if no trace parameters are specified and no diagnostic points are configured, only the  default parameter values will be written to the trace file. The trace log is located in the LOG directory of your project.

Important: Enabling tracing beyond the defaults will reduce the performance of your OPC Communication and your PC. Tracing should only be enabled for the purpose of diagnosing an issue, should one arise.

Port Parameters that manage Trace output






Trace output can be written to either a circular log file (1) or to a flat file (0). If CircularLog=1, trace output goes to the circular log.

The circular trace log is named according to the CIMPLICITY Port it represents. MASTER_OPC_0.LOG for the first port, MASTER_OPC_1.LOG for the next port, etc.

If CircularLog=0 (flat file), the file is also named according to the CIMPLICITY Port, but the convention is slightly different:
for the first port,
for the next port, etc.

The only advantage of the flat file is that, since it never wraps around, no trace data will be overwritten (nothing is lost). This is only an issue when a large amount of trace data is written over an extended period of time. As you will see, output to a flat file is seldom necessary to diagnose an issue. Flat files can grow very large, very quickly. You must monitor their size closely.

If the flat file is used, the LogFileSize parameter is ignored.


This property determines the maximum size the circular log can grow to before it wraps around and begins writing to the top of the file again. The default size is one megabyte (1000000).

If you find that the circular log wraps too soon and begins overwriting old trace records you feel may be important to the diagnosis of a problem, increase this property to prolong the wrap.

More information

Setting OPC port settings properties.

Setting OPC device settings properties.

Enabling tracing.

Viewing trace information.

About OPC Client.