Rockwell Automation MMCL Using the Mining, Mineral, and Cement Library (MMCL) in RSLogix 5000 Appli - Manual (Page 27)

Publication RA-UM002B-EN-P - November 2010
Control Group 27
Local Operation
Local operation can at any time be selected, i.e. a group may be running, while
certain machines within the same group, can be started and stopped locally.
Automatic operation uses the control sequence described above and is
transferred from the operator panel (template), by means of the group
start/stop pushbuttons and monitors for mimic displays and alarming.
Regardless of local operation, a group sequence can, at any time, be started,
when all start interlocks are satisfied.
Local operation is required for maintenance and test purposes. It is only
possible, with operator permission, to allow, or deny, local operation, for an
entire group, by means of the local button. Local operation, is always cancelled
by the CtrlGrp, if the sequence is interrupted by a Immediate Stop.
Interlock Release
Each group can be operated with released interlocks, for commissioning, or
other special purposes. In the interlocked released mode, the inputs
IntlStart/IntlStop/IntlImmStop 0..n are inactive, however the messages are
still displayed (see CtrlGrp ModuleData Tag .Var.INR).
Power-Dip Suppression
Power-dip refers to short (less than 300 ms) main power interruptions, caused
by lighting, high voltage switching etc.
Because the main control equipment (field devices, interposing relays,
I/O-racks and PLCs as well as HMI PC's) are fed by uninterrupted power
supplies (UPS), it is possible to monitor power interruptions continuously and
prevent unnecessary shutdowns, as well as alarm messages, i.e. ignore short
power interruptions and suppress incorrect alarms caused by power outages.