PCI Bus Contention and TL Space

Large Pro Tools TDM systems running TL Space TDM in conjunction with video capture and playback or other PCI cards may encounter –6042 errors. These errors are caused when the Pro Tools DAE engine cannot transfer audio track data from the computer to the Pro Tools card over the PCI bus quickly enough. The error typically occurs when TL Space attempts to use the PCI bus to load impulses. PCI bus contention can be addressed with the following steps.

First, you may wish to locate more demanding PCI cards on the main PCI bus rather than in an expansion chassis. By locating the PCI cards away from Pro Tools DSP cards, PCI contention is typically reduced.

Secondly, assign more DSPs to the Pro Tools Playback Engine. Open the Playback Engine dialog and increase the number of DSPs per the Number of Voices.

If this does not resolve bus contention issues, the PCI Throttle control can be adjusted upwards one step at a time until the –6042 errors stop. For example, the default setting for a Macintosh G5 system is 33% and it can be increased in two steps to 100% until the bus contention is resolved. As more PCI throttling is used, TL Space will take longer to update the data on the DSP chip(s) running TL Space.

The PCI Throttle control can be adjusted in Preferences mode. Settings take effect immediately across all instances of TL Space. This control offers the settings shown in the following table.

 

Setting	Effect
Off	No PCI throttle control—maximum PCI contention
33%	Default setting for Macintosh G5 systems
66%	Default setting for Windows XP systems
100%	Maximum PCI throttle—minimum PCI contention

 

Increasing the PCI throttle control will reduce TL Space performance as PCI activity is reduced.

For most users, the PCI throttle control provides optimum performance at the default setting and should not be adjusted.