Foxboro ISA-S71.04-1985 Environmental Conditions for Process Measurement and Control Systems

APACS+ Subsystems

An FCP280. FCP270 or FCM100Et/FCM100E

baseplate is installed in the MODULPAC enclosure

with single or redundant modules. The baseplate has

a built-in Fieldbus termination assembly. The

I/O module power supplies and MODULRACs are

retained in the cabinet.

The MODULRACS, used to house I/O modules, are

reused to house the DCS FBMs. All termination

assemblies in the local, adjacent, and remotely

marshalled MODULPACs remain intact with their

termination cables and field wiring.

APACS+ I/O modules are removed from the

MODULRAC and replaced by a corresponding DCS

FBM that mates to the original power/signal

connector and termination cable connector on the

back of the MODULRAC. This DCS FBM provides

original I/O functionality of the process inputs and

outputs.

Ladder Logic Implementation

Ladder logic for an APACS+ system is implemented

in the ACM controllers, not in the I/O modules. Thus,

any digital I/O point in the system can be used as an

input or output to the ladder logic running in the

ACM. A similar capability exists with the migrated

APACS+ system through the use of sequence control

logic in the FCP280. FCP270 or ZCP270 Control

Processor.

Foxboro control block ladder logic is implemented by

using a combination of logic which executes directly

in the digital I/O modules and sequence control logic

in the Control Processor. This same capability exists

in the AID115. AID230. AOD115. and ADO125

APACS+ migration modules. The channel

configurable ASAM01. AEAM01. ASDM24 and

ASDM48 I/O modules implement ladder logic only by

using sequence control logic in the Control Processor

similar to the original APACS+ system.