CHARM I/O Cards (CIOCs) and CHARMs, together called CHARM I/O, represent a major change in I/O design, wiring, and installation. With traditional I/O, the field wiring must be connected to a single I/O channel assigned to the same controller that is hosting the control strategy. This requires early design decisions that are often only estimates that are then changed late in the project. Late changes can result in the need for new hardware and signal rewiring that can impact the project schedule and increase the project costs.
With CHARM I/O, field wiring can be designed and installed without detailed engineering of the control strategies. Channel types are defined individually when the appropriate CHARacterizing Module, called a CHARM, that matches the field device (AI, AO, DI, DO and so on) is installed. I/O channels can be assigned to controllers as needed by the control strategy.
Responding to late design changes is easy with CHARM I/O:
Signals can be changed from discrete to analog by changing the CHARM to match a new field device. No rewiring to a different I/O card is required.
Control modules and their I/O can be reassigned to a different controller without changing the hardware or rewiring.
New channels can be added online.
New CHARM I/O Cards can be added online only when and where they are needed.
CHARM signals are processed and made available to controllers by a CHARM I/O Card.
For information on Logic Solver CHARMs (LS CHARMs) refer to CHARMs Smart Logic Solver (CSLS) SIS Systems in the DeltaV Safety Instrumented System manual in Books Online.