Applies To:
  • CitectSCADA 1.00 1.01 1.10 1.11 1.20 2.00 2.01

You may get the error messages "Lan Out of Buffers" errors even though the maximum value of Lan.Read.Pool and Lan.Write.Pool have been set. These errors generate hardware alrams, can increase the CPU to 100% for an extended period of time, and could cause Citect to crash or hang.

The maximum values of the Lan.Read.Pool and Lan.Write.Pool are usually sufficent to handle even huge network systems (see Q1262). However you can cause network overload by configuring Citect incorrectly. One possible cause is if you are overloading a DISK PLC. You can do this by codeing a While loop of the CICODE without proper SLEEP, which writes data continiously to the DISK PLC (see Q1031). To solve the problem you must put a proper SLEEP statement to slow down the disk access, and/or to move the disk plc to a standby IO server, if there is one.

The PAGE DRIVER command in the Kernel will tell you wether you are using the disk plc too frequnetly.

See also Q1131 and Q1060.