Maple Systems HMC7000 Series - Manual (Page 72)

HMC7000 Series I/O Module Guide
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1010-1043 Page 71 of 85 Rev. 02, 11/08/2013
Common Terms for I/O Modules
This section defines some common terms used to describe various types of input and output
modules. The terms explained below are generic descriptions. Be sure to consult the datasheet
for the specific requirements when installing and wiring a module.
Digital Modules
Digital Modules provide physical connections and interpretations of input devices using discrete
signals. The input is represented in the PLC input registers as a 1 for the on state and 0 for the
off state. Each digital input terminal is associated with an internal Input Coil (X) in the tag
database of the HMC7000. Similarly, each digital output terminal is associated with an Output
Coil (Y).
Analog Modules
Analog Modules provide physical connections and interpretations of input devices using analog
signals. The input range depends on the type of input device. Configure analog inputs to work
with current or voltage sources. Each analog input terminal is associated with an internal Input
Register (XW) in the tag database of the HMC7000. Similarly, each analog output terminal is
associated with an Output Register (YW).
Sinking versus Sourcing Inputs
These terms refer to the type of digital inputs or outputs used. A sourcing I/O provides a voltage
source, and a sinking I/O provides a ground. Any module that is not bidirectional (meaning
current can go in either direction) requires that the circuit conduct current in a specific direction.
For a sourcing module, the current flows out of the expansion module terminal and into the
common (signal ground) terminal. The term source indicates the terminal on the expansion
module provides the current to the switch contact or load.
For a sinking module, the current flows into the expansion module terminal and out of the
common terminal on the I/O module. The term sink indicates the terminal takes in the current
from the switch contact or load.