
B–63833EN/03
8. CONNECTING MACHINE INTERFACE I/O
109
The following cautions must be observed when using I/O signal receivers
and drivers for the machine interface.
DI signals are basically of the sink type (a type that drains energy). Some
DI signals, however, can be set to either sink type or source type (a type
that supplies energy). See the description of the I/O board in the following
section for details.
A common signal is provided for selectable receivers. Whether the
common signal is connected to 0 V or 24 V determines whether a DI
signal is of sink or source type.
A source type DI signal is undesirable from the viewpoint of safety,
however, because if the input signal line is grounded, it will be latched in
the same state as that existing when the contact is closed. It is
recommended that all DI signals be set to sink type.
Always connect the common signal to either 0 or 24 V; do not leave it
open.
The driver of DO signals is source type (a type that supplies energy,
non–insulating).
If a system alarm occurs in a control unit of the Series 0i, all I/O board
drivers are turned off. Keep this in mind when setting up a machine
sequence.
The same situation can occur if the power to the control unit is turned off
independently.
8.2
CAUTIONS
8.2.1
DI Signals and
Receivers
8.2.2
DO Signals and Drivers