As the cost of computational power decreases, more DCSs and bus-based control
systems (digital communication based control systems), are implementing
on-off control as well. Some of these systems use ladder diagram programming,
while others use function-block-based programming. Suffice it to say that function
blocks are programmed using a set of symbols that, once understood, can
be read and interpreted relatively easily. Electronic controllers such as single
loop digital controllers (SLDC) have some integral on-off control capabilities.
Some field transmitters even have on-off control capability. The on-off control
capabilities of electronic configurable devices are almost limitless.