Computer Hardware User Manual

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Example In the following example, TERM(48) is used to switch the Programming Console
to TERMINAL mode when 00000 is ON. Be sure that pin 6 of the CPU Unit’s DIP
switch is OFF.
TERM(48)
000
000
000
00000
Address Instruction Operands
00000 LD 00000
00001 TERM(48)
000
000
000
5-25-7 WATCHDOG TIMER REFRESH – WDT(94)
T: Watchdog timer value
# (00 to 63)
Ladder Symbols Definer Data Areas
@WDT(94) TWDT(94) T
Description When the execution condition is OFF, WDT(94) is not executed. When the
execution condition is ON, WDT(94) extends the setting of the cycle monitor
time (watchdog timer) set in DM 6618 of the PC Setup. The default setting is 120
ms.
Timer extension = 100 ms x T
Where, T = 00 to 63 (4-digit BCD)
Precautions The cycle monitor time (watchdog timer setting) can be set to a maximum of 99 s
with the PC Setup. The WDT(94) instruction can be used to extend the cycle
monitor time to a maximum value of 6400 ms, but only the portion of the cycle
used for instruction execution is extended.
WDT(94) can be executed more than once in a cycle, but the cycle time can’t be
extended by more than 6400 ms total. Any extension over 6400 ms will be ig-
nored. Another WDT(94) instruction won’t be executed if the cycle time has al-
ready been extended by 6400 ms.
Timers might not function properly when the cycle time exceeds 100 ms. When
using WDT(94), the same timer should be repeated in the program at intervals
that are less than 100 ms apart. TIMH(15) should be used only in a scheduled
interrupt routine executed at intervals of 10 ms or less.
Flags There are no flags affected by this instruction.
5-25-8 I/O REFRESH – IORF(97)
St: Starting word
IR 000 to IR 049, IR 100 to IR 199,
SR 400 to SR 450
Ladder Symbol
E: End word
IR 000 to IR 049, IR 100 to IR 199,
SR 400 to SR 450
Operand Data Areas
IORF(97)
St
E
Limitations IORF(97) can be used to refresh I/O words allocated to I/O Units, Special I/O
Units, and Interrupt Input Units mounted to the CPU or Expansion I/O Racks.
Special Instructions Section 5-25