Debubbing FLink transactions

Included as of version: 1.6.4

In order to facilitate error analysis in connection with FLink systems, each command that RetailForce Fiscal Middleware transmits to FLink is stored in a file ring buffer. The last 15 requests are then stored in the "flink" directory of the client data directory (C:\ProgramData\RetailForce\Fiscal Webservice\<client guid>) for possible later analysis.

If the command contains a document, the DocumentGuid is included in the file name for easier referencing.