Applies To:
  • CitectSCADA 5.xx

While running Citect under certain peak loading conditions you may experience the error "Out of Buffers" or "Out of Buffers lan.write.pool". 

In more recent versions of Citect, networking has become a lot more saturated. With faster computers and network technologies customers are driving their Citect software harder. With this, more and more customers are reporting that even with the maximum settings of 8096 for [lan]readpool and [lan]writepool they are still getting out of buffers errors. This can happen for instance if several clients are trying to access large amounts of trend data.

In the past these settings affected performance as they would use vital Microsoft Windows resources. However under 32 bit windows this is no longer an issue. Even though the maximum has now been increased to 32760 for both read and write pool buffers it is still maintained that there are times when a high network loading is not reasonable. These buffers should only be used for peak demand. If you find that network rates are constantly high then it is possible that:

1. your project may be configured incorrectly

2. your project architecture along with your network topology may be compounding an issue.

Before arbitrarily increasing these values these and other factors should be considered first or else you may be hiding a more sinister issue.

Refer to KB Article Q3739 for a discussion on typical network rates.

Citect has confirmed this to be a problem in CitectHMI/SCADA versions 5.XX. This problem has been fixed in version 6.00.


buffers lan.write.pool