Menu Tools > Expert Options...
Expert Options are additional settings for specialized applications with additional requirements (e.g. high time tagging accuracy).
Performance
Communication Driver Mode
Use External / High Priority Process mode to work around a common problem for any Windows user mode application: unspecified delays and timing inaccuracies can be introduced by the Windows task/process scheduling, especially if you are running other applications besides Docklight.
External / High Priority Process mode is recommended for high accuracy / low latency monitoring using the Docklight Tap.
NOTE: For even higher and guaranteed time tagging accuracy, use the Docklight Tap Pro / Tap 485 accessories. Their accuracy does not depend on Windows and driver latencies, and High Priority Process mode is not required for Tap Pro and Tap 485 applications.
In External / High Priority Process mode, the data collection in Docklight becomes a separate Windows process with "Realtime" priority class. It will be executed with higher priority than any other user application or additional application software such as Internet Security / Antivirus. For best results Docklight needs to be Run as administrator. Otherwise the data collection process will run with the maximum priority permitted by the OS, but not "Realtime class".
External / High Priority Process mode must be used with care, especially when you intend to monitor a high-speed data connection with large amounts of data. The PC might become unresponsive to user input. To resolve such a situation, simply "pull the plug": First disconnect the data connections or the monitoring cable to bring down the CPU load and restore the responsiveness. Then choose 
Stop communication in Docklight.
NOTE: See the section How to Obtain Best Timing Accuracy for some background information on timing accuracy.
Docklight Monitoring Mode
When Monitoring Serial Communications Between Two Devices, all received data from one COM port is re-sent on the TX channel of the opposite COM port by default ("Data Forwarding"). This is intended for special applications that require routing the serial data traffic through Docklight using standard RS232 cabling.
Use the No Data Forwarding Expert Option for applications with two serial COM ports where you need to avoid that any TX data is sent. This can be used to improve performance when using a Docklight Monitoring Cable, or to work around problems caused with unstable serial device drivers.
For Docklight Tap applications (e.g. using Communication Channel TAP0 / TAP1), the 'Data Forwarding' setting has no effect. The Docklight Tap is accessed in read-only mode always, and no data is forwarded.
Devices
Windows COM Devices
Use Disable I/O error detection when receiving repeated error messages like this:
DOCKLIGHT reports: General I/O error on COM1
NOTE: Docklight uses Windows Serial Communications in "overlapped I/O" mode for best efficiency and timing accuracy, and it continuously evaluates errors from the related Win32 API calls. In rare situations like COM devices using faulty or outdated COM device drivers, such errors can appear even in standard read/write operation. In this case, you can use this option to revert to the behavior of Docklight V2.2 and earlier versions: simply ignoring such errors.
Tap Pro / Tap 485
The firmware update functions for our Docklight Tap Pro / Docklight Tap 485 hardware accessories are only required in rare situations. E.g. if you are using an older device (< year 2017) which does not support the baud rate scan feature yet.