Rockwell Automation 1746-XXXX SLC 500 32-Channel Digital I/O Modules Installation Instructions - Manual (Page 9)

SLC 500™ 32-Channel Digital I/O Modules 9
Publication 1746-IN028A-EN-P - October 2003
Auto Reset Operation
Short Circuit/Overload Current Diagnostics
If a short circuit or overload current condition occurs on an output channel:
1. The E-Fuse LED will illuminate provided that power is applied to the
module. (power required: 5V dc via backplane and load power via an
external supply)
2. All other channels continue to operate as directed by the CPU (processor)
module.
Recovery From Channel Shutdown
1. Remove the SLC 500 system power and correct the conditions causing the
short circuit or overload current condition.
2. Restore the SLC 500 system power. The module automatically resets and
resumes control of the output channel and associated load.
IMPORTANT
The 1746-OB32E performs auto-reset under overload
conditions. When an output channel overload occurs as
described above, that channel limits current within
milliseconds after its thermal cut-out temperature has been
reached. While in current limit, the output channel can cool
below the thermal cut-out temperature, allowing the module
to auto-reset and resume control of the output channel as
directed by the processor until the thermal cut-out temperature
is again reached.
Removing power from an overloaded output channel would
also allow the output channel to cool below the thermal
cut-out temperature allowing auto-reset to occur when power
is restored. The output channel would operate as directed by
the processor until the thermal cut-out temperature is again
reached.
To avoid auto-reset of an output channel under overload
conditions, an external mechanical fuse can be used to open
the circuit when overloaded.