INTRODUCTION
WBPEEUI240752A0
2 - 1
SECTION 2 - DESCRIPTION
INTRODUCTION
This section explains the inputs and input circuitry , control
logic, logic power and connections for the IMDSI1
Digital
Input modules. The DSI is a digital input interface to a
multi-function processor (MFP), multi-function controller
(MFC), or logic master module (LMM). These control modules
provide the control functions. A control module communicates
with its I/O modules on a I/O expander bus as shown
in Figure
. Each I/O module on the I/O expander bus has a
unique address set by address dipswitch S1 (Fig.
INPUTS
Digital field inputs are voltages of 24 VDC, 48 VDC, 125 VDC
or 120 VAC rms. These voltages indicate an energized (ON)
field device; a 0 volt input indicates a de-energized (OFF) field
device. The DSI have a fixed input debounce filter for DC
inputs to allow for contact debounce time (17 millisecond
response time).
The IMDSI13 (+24 VDC) module and the IMDSI14 (+48 VDC)
module have a fixed configuration and do not require any
jumper selections. The IMDSI15 (+125 VDC/120 VAC) module
has jumpers to select DC or AC mode. The IMDSI12 (+24, +48,
+125 VDC or 120 VAC) module has jumpers to select the DC
or AC mode and jumpers to select the working voltage. Refer to
the Installation section for an explanation of the jumper con-
nections.
NOTE: Due to the number of pins on the P3 connector, twelve
inputs are separate while the remaining two pairs share input termi-
nals. The positive (+) side of point 7 and 8 are tied together in each
group (refer to Table
). These points must use the same contact
voltage (24 VDC, 48 VDC, 125 VDC or 120 VAC) set by the jumpers
on the IMDSI12 module, or according to the relevant IMDSI1
mod-
ule working voltage.
Input Circuits
Figure
is a block diagram illustrating signal flow through
the module. The input isolation block consists of current limit-
ers and optocouplers to isolate the 16 field inputs from the
module circuitry. The input circuits provide 1500 VDC isola-
tion between input and logic circuitry and other input chan-
nels. Refer to Table
Digital input high impedance provides additional (passive) pro-
tection from high energy transients of field digital inputs.
