ABB Symphony Harmony Series Instruction page 50

Description and Operation
Introduction
Module Description
Inputs
WBPEEUI240767B0
This section explains the inputs and input circuitry, control
logic, logic power and connections for the IMDSI13, IMDSI14,
and IMDSI22 Digital Input Modules. The DSI module is a digi-
tal input interface to Harmony controller. These controllers
provide the control functions. A controller communicates with
its I/O modules on an I/O expander bus as shown in Figure
1-1. Each I/O module on the I/O expander bus has a unique
address set by address dipswitch S1 (Refer to
The digital input module consists of a single printed circuit
board that occupies one slot in a module mounting unit. It
monitors two separate groups of eight digital inputs. Twelve
inputs are isolated from each other; the remaining two pairs
share common positive input lines.
Two captive screws on the module faceplate secure it to the
module mounting unit. Sixteen front panel LED status indica-
tors (group A and group B) display the input status and pro-
vide aid in system test and diagnosis.
The digital input module has three card edge connectors for
external signals and power (P1, P2 and P3). P1 connects to
common (ground) and +5 VDC power. P2 connects the module
to the I/O expander bus to communicate with a controller. P3
inputs the digital signals using a cable connected to a termina-
tion unit. The terminal blocks (physical connection points) for
field wiring are on the termination unit.
Digital field inputs are voltages of 120 VAC, 24 VDC, 48 VDC,
or 125 VDC. These voltages indicate an energized (on) field
device; a zero volt input indicates a de-energized (off) field
device. The DSI modules have a fixed input debounce filter for
Section 2
Input Input Circuits Circuits).
Input Circuits Input Circuits
2 - 1