6. CONNECTION OF I/O UNITS TO
DO (output signal) alarm detection
The DO driver of the I/O module is capable of detecting an overcurrent
and measuring its own temperature. If an accident, such as connecting the
cable to ground, causes an abnormal increase in the load current or in the
driver temperature, a protection circuit, which is provided for each DO
driver (1 byte), is activated which keeps the DO signal for the relevant 1
byte in the OFF state until the cause of the problem is eliminated. Even
if this occurs, the Power Mate and the I/O module continue operating. The
DI address (Xm+15) identifies which DO driver has detected an alarm.
The following table shows the correspondence between the DI address
(Xm+15) bits and the DO addresses. Bit value “1” indicates that the
corresponding DO driver has detected an alarm. The contents of the
Xm+15 area can be checked by using the DGN screen of the Power Mate
or by performing the alarm processing for the area in advance by using
Ladder. This helps alarm detection and recovery.
address and bit
DO address Remarks
Xm+15.7 Yn+7 Reserved
If the ladder program does not perform alarm processing for
Xm+15, the Power Mate cannot detect an error (if occurs)
in the DO driver.