6. CONNECTION OF I/O UNITS TO
The output signal driver can output up to eight signals.
The driver element monitors the current of each output signal. If an
overcurrent is detected, the output of that signal is turned off. Once a
signal has been turned off, the overcurrent will no longer exist, such that
the driver turns the signal on again. Therefore, in the case of a ground fault
or overload, the output of a signal will be repeatedly turned on and off.
This also occurs when a load which causes a high surge current is
The driver element contains an overheat detector, which turns off all eight
output signals if the temperature in the device exceeds the set value as a
result of an overcurrent caused by a ground fault or some other failure.
This off state is held. To restore signal output, logically turn the output
off then back on again, for each signal, after the temperature falls below
the set value. Signal output can also be restored by turning the system
power off then back on again.
If the output of a signal cannot be turned on even though the diagnostic
indicates that the signal is on, that signal or another signal being handled
by the same element may be overloaded, thus causing the eight output
signals to be turned off. In such a case, turn the system power off and
eliminate the cause of the overload.
OHD: Overheat detection circuit
OCD: Overcurrent detection circuit
The power for operating this driver element is supplied from DOC (24
The following restriction applies to the connection of the output signals.
The following parallel connection of output pins shall not be used.
Output signal driver
D Driver element block