Tuning the Driver

Driver tuning can be performed through modifying the update rate and throughput can be altered at several levels.

Each register block has a normal and demand scan rate setting associated with it. The units used are seconds, and tenths of a second, and define how often the block is scanned in either mode. Scanning can be disabled by setting the scan field value to `F' - however the register block will be scanned once on driver startup.

The nap time may be changed with the nap command line argument. The larger the nap time the less system loading is incurred. The default nap time is a reasonable size and the nap should only need to be increased if the system is running very slowly or if there are long communications delays. The utility program plcstat may be used to view the shared memory image.