TsctlAIOChannelPrecisionDesc

This function sets and returns the precision for the specified channel ch to be the given number of bit prec. If the channel is not currently enabled, then the precision will not take effect until ChannelEnable is called for this channel. Otherwise the change will take place immediately.

If a value of 0 is passed for prec, the current value in effect is returned unchanged.

Upon failure, a value of 0 is returned to indicate that the requested precision cannot be set. If the precision will not take effect immediately then this cannot occur, so the current precision will be returned, since the one passed has not yet taken effect.