Applies To:
  • CitectSCADA 1.20, 2.01
Summary:
The error message 'Out Of Buffers <name>' will be logged to the SYSLOG.DAT file when Citect has run out of buffers. The <name> is the name of a Citect buffer pool that has run out.

Citect creates pools of memory buffers to be used for various processes. Most of these buffer pools can grow and shrink as the demand rises and falls. However, some buffers pools are accessed under interrupt conditions, and therefore must be of fixed size. These buffers pools can be overloaded and run out under some conditions. The size of these buffer pools has been set for normal operation. However with large databases, and/or high loading conditions these buffers may run out. 

Solution:
The size of the buffer pools can be adjusted by parameters in the CITECT.INI file. So you may increase the number of buffers until the errors go away. The only dissavantage in setting these buffers pools too large is you will wast Windows memory. The following table shows the name of the pool as well as the associated INI option.
 
Name Parameter Default Description
lan.read.pool [LAN]ReadPool *64 This buffer pool is used to unload data from the network. Large Networked Citect systems will require this to be increased. Small 32, Median 96, Large 132, Huge 256. When Citect runs short of this pool, the hardware error 'Out of buffers' will be generated and this will degrade the network performance.
lan.write.pool [LAN]WritePool *64 This buffer pool is used to buffer write data to the network. Large Networked Citect systems will require this to be increased. Small 32, Median 96, Large 132, Huge 256. When Citect runs short of this pool, Citect will close the Network session associated with the Write. This will cause the Hardware error 'SESSION CLOSED' and will degrade the network performance.
lan.stack.pool [LAN]Stack 4 This is a pool of interrupt stacks used by the NetBIOIS interface. No hardware error is generated when this pool is exhausted. Citect will use the default stack and there is no loss of performance. This stack is not allways required, so you may disable the stack by setting the option to 0. If however after you disable the stacks, Citect or your computer crashes, re-enable the option and increase the number of stacks. Range is 4 to 32.
NCBPool [LAN]NCBPool 30 This buffer is used to buffer NCBs to the serial NetBIOS. When Citect runs short of this pool, you will get Network errors on the serial and other LANs. This may cause sessions between clients and servers to fail. This will cause the hardware error 'No Server could be found' and possibly other network hardware errors.
NCBPoolMem [LAN]NCBPool, Yes this is the same as above! 30 This buffer is used to buffer NCBs to the serial NetBIOS. When Citect runs short of this pool, you will get Network errors on the serial and other LANs. This may cause sessions between clients and servers to fail. This will cause the hardware error 'No Server could be found' and possibly other network hardware errors.
dat.read.pool [CitectForDOS] ReadPool 32 This buffer pool is used to unload data from the network for Citect for DOS support. When Citect runs short of this pool, the hardware error 'Out of buffers' will be generated and this will degrade the network performance.

This pool is only used for Citect for DOS support. If Citect for DOS support is not enabled this pool is not created.

dat.write.pool [CitectForDOS] WritePool 32 This buffer pool is used to buffer write data to the network for Citect for DOS support.

This pool is only used for Citect for DOS support. If Citect for DOS support is not enabled this pool is not created.

The default size for these pools was 32 before versions 1.20 and 2.01. 
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