Netlinx Queue and Threshold Settings(not for NX​​)

Summary

Netlinx masters employ a number of internal settings that affect it's handling of messages to and from devices and processes.

As mentioned in Tech Note 476, changing these values without care can negatively impact system performance. However, sometimes the symptoms suggest that an adjustment is appropriate.

Symptoms

• Frequent thread "pended" messages in the master's log.

• Frequent non-zero numbers in "show buffers" results. **

• Random system sluggishness independent of system input/output or programming.

• Random system lockups independent of system input/output or programming.

**The normal operation of a master will show some activity in the "show buffers" values, but the numbers will quickly return to 0s during idle periods.

Cause

Many aspects of system design, programming, and installation can cause these symptoms. Ethernet traffic - whether or not related to the control system - can also cause some of these symptoms.

Improper settings of queue and threshold sizes may also be a culprit in the above symptoms.

Resolution

It is critical that one investigates and eliminates any other potential cause of these symptoms before blindly applying these adjustments. Otherwise, you may mask real problems that will resurface later. Do not hesitate to consult with AMX Technical Support about any issues, before or after attempting improvements.

AMX has published, as part of it's Design Xpress (DXP) package, a file that can be included into any existing Netlinx program, which will optimize the queue and threshold sizes for most systems.

Usage

1. Contact Technical Support to obtain the Queue_and_Threshold_Sizes.axi file.

2. Place the file in the directory pointed to by the Include Files parameter in NetLinx Studio's compiler preferences, or place it in the directory with your code. Add it to your Workspace.

3. Use a #INCLUDE statement in your program's DEFINE_START section: #INCLUDE'Queue_and_Threshold_Sizes.axi'.

4. Note that the master will reboot twice after loading this code for the first time.​