ABB Symphony Harmony Series Instruction page 54

I/O Expander Bus
Universal I/O Expander Bus Interface
Mounting Hardware
WBPEEUI240767B0
The I/O expander bus is a high speed, synchronous, parallel
bus. It provides a communication path between controller and
I/O modules. The controller provides the control functions and
the DSI module provides input to the controller. The P2 card
edge connector of the DSI module and controller connect to
the I/O expander bus.
The I/O expander bus is parallel signal lines located on the
module mounting unit back plane. A 12-position dipshunt
placed in a connection socket on the module mounting unit
back plane connects the I/O expander bus to the controller
and I/O modules. Cable assemblies can extend the I/O
expander bus to six module mounting units.
A controller and its I/O modules form an individual subsystem
within a process control unit (PCU). The I/O expander bus
between controller and I/O module subsystems must be sepa-
rated by leaving a dipshunt socket empty or not connecting
the module mounting units with cables.
The DSI module uses a custom gate array to perform the I/O
expander bus interface function. All the control logic and com-
munication protocol are built into an integrated circuit. This
integrated circuit provides the following functions:
Address comparison and detection.
•
Function code latching and decoding.
•
Read strobe generation.
•
Data line filtering of bus signals.
•
On-board bus drivers.
•
Harmony rack I/O modules and termination units mount in
standard enclosures (CAB-01, CAB-04, CAB-12). The number
of modules that can be mounted in a single cabinet varies.
An IEMMU11, IEMMU12, IEMMU21, or IEMMU22 Module
Mounting Unit and an NFTP01 Field Termination Panel are
used for module and termination unit mounting respectively
I/O Expander Bus
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