Use the CEM function block to define interlock and permissive logic that associates as many as 16 inputs (CAUSEn parameters) and 16 outputs (EFFECTn parameters). Use the block's MATRIX parameter to identify one or more causes that cause each effect to trip. When a CAUSEn becomes active, all effects associated with that CAUSEn also trip.
The CEM block does not support modes.
A CEM block provides the logic for one or more functions. CAUSEn inputs are typically wired from upstream voter function blocks, but may come from any source indicating either an active (0) or inactive (1) process trip condition. The EFFECTn outputs are typically wired to downstream output function blocks.
The normal operating value of the output is 1 (On) and the tripped value is 0 (Off).
By default, the block has four CAUSEn inputs and one EFFECTn output. You can set the number of causes and effect using the NOF_CAUSES and NOF_EFFECTS extensible parameters. In addition, you can use the DESC_CAUSEn and DESC_EFFECTn parameters to label causes and effects.
The following diagram shows the internal components of the CEM function block.
