Chapter 25
Control Instructions
25–8
ATTENTION: If you start instructions such as timers or
counters in an MCR zone, instruction operation ceases when
the zone is disabled. Reprogram critical operations outside
the zone if necessary.
The TOF timer will activate when placed inside of a false
MCR zone.
The MCR instruction is not a substitute for a hard-wired
master control relay. We recommend that your
programmable controller system include a hard-wired master
control relay and emergency stop switches to provide
emergency I/O power shut down. Emergency stop switches
can be monitored but should not be controlled by the ladder
program. Wire these devices as described in the installation
manual.
!
Temporary End
TND
Output Instruction
(TND)
(TND)
F1
F2
F3
F4
F5
ZOOM on TND –(TND)– 2.3.0.0.2
NAME: TEMPORARY END
EDT_DAT
HHT Ladder Display:
HHT Zoom Display:
Ladder Diagrams and APS Displays:
(online monitor mode)
This instruction, when its rung is true, stops the processor from scanning the
rest of the program file, updates the I/O, services communications, and
resumes scanning at rung 0 of the main program (file 2). If this instruction’s
rung is false, the processor continues the scan until the next TND instruction
or the END statement. You can use this instruction to progressively debug a
program, or conditionally omit the balance of your current program file or
subroutines.
When used in a subroutine, this instruction does not function the same as an
END or RET (which causes the processor to resume operation in the
previous file). The processor stops where it is, updates I/O, services
communications, and goes to the beginning of the main program.
Temporary End (TND)
