Omron DRT2 SERIES DEVICENET SLAVES - OPERATION MANUAL 04-2008 Operation Manual page 280

Advanced Environment-resistive Terminals
Automatic Recovery
Mode Restrictions
be turned OFF to prevent damage to the transistor, the Load Shorted Flag will
be turned ON, and the indicator will light red.
In automatic recovery mode (Fig. 2), the short-circuit protection status will be
automatically cleared and the output current will start to flow again when the
transistor's shutdown temperature (Tj) drops to the reset temperature (Tr).
In manual recovery mode (Fig. 3), the short-circuit protection status will be
held even when the transistor's shutdown temperature (Tj) drops to the reset
temperature (Tr), and recovery will occur when the Unit is reset by turning
OFF the I/O power supply or the Unit's power supply.
Fig. 1 Normal Operation
ON
OUT
OFF
ON
Iout
OFF
ON
LED
Status
OFF
Fig. 2 Overload or Short-circuit (Automatic Recovery Mode)
ON
OUT
OFF
Tj =Tstd Tj =Tr
I
lim
ON
I
OUT
OFF
ON
ERR
OFF
Fig. 3 Overload or Short-circuit (Manual Recovery Mode)
ON
OUT
OFF
I lim
ON
Iout
OFF
ON
LED
Status
OFF
I/O power ON
supply
OFF
The Unit has load short-circuit protection, but automatic recovery mode is
designed to protect the internal circuits specifically from a brief load short-cir-
cuit.
In automatic recovery mode, the Unit's load short-circuit protection is auto-
matically cleared when Tj = Tr, as shown in Fig. 2. Therefore, as long as the
cause of the short-circuit is not removed, the output's ON/OFF operation will
repeat.
If the Unit is left with a short circuit, the internal temperature will rise, causing
damage to the Unit. Always remove the cause of an external load short-circuit
promptly.
Note When an external load short-circuit is detected, the External Load Shorted
Flag will turn ON in the Unit's Status Area and the indicator corresponding to
the shorted output contact will turn ON. An OR for all contact status will output
to the Short-circuited Flag.
OUT: Output contact
IOUT: Output current
ERR: Alarm output, ERR indicator
I lim: Current limit
Tj: Transistor junction temperature
Tstd: Thermal shutdown temperature
Tr: Reset temperature
Tj =Tstd
Section 6-4
259