163
TR Area
Section 3-4
I/O Hold Bit is OFF, all IR and LR bits will be reset when the PC starts opera-
tion.)
Turn this bit ON and OFF from a Programming Device.
DM 6601 in the PC Setup can be set to maintain the previous status of the I/O
Hold Bit when power is turned ON. When this setting has been made and the
I/O Hold BIt is ON, the status of bits in the IR and LR areas will not be cleared
when the power is turned ON.
SR 25215
(Output OFF Bit)
When this bit is turned ON, all outputs will be turned OFF and the CPU Unit’s
INH indicator will light. As long as the Output OFF BIt is ON, outputs will
remain OFF even if output bits are turned ON by the program.
Pulse outputs from Transistor Output Units and Pulse I/O Boards will remain
OFF as long as the Output OFF Bit is ON. If a High-speed Counter Board has
been installed, the Board’s external outputs (1 to 4) will remain OFF as long
as the Output OFF Bit is ON.
When the Output OFF Bit will normally be OFF, turn it OFF regularly from the
program. If the Output OFF BIt is not turned OFF from the program, its ON/
OFF status will be retained when the power is OFF (although its status may
not be retained if the backup battery fails.)
SR 25308
(Battery Low Flag)
A setting can be made in the PC Setup (DM 6655) so that these errors will not
be generated.
SR 25309
(Cycle Time Over Flag)
A setting can be made in the PC Setup (DM 6655) so that these errors will not
be generated.
3-4
TR Area
When a complex ladder diagram cannot be programmed in mnemonic code
just as it is, these bits are used to temporarily store ON/OFF execution condi-
tions at program branches. They are used only for mnemonic code. When
programming directly with ladder diagrams, TR bits are automatically pro-
cessed for you.
The same TR bits cannot be used more than once within the same instruction
block, but can be used again in different instruction blocks. The ON/OFF sta-
tus of TR bits cannot be monitored from a Programming Device.
Examples showing the use of TR bits in programming are provided on
page 195.
3-5
HR Area
These bits retain their ON/OFF status even after the CQM1H power supply
has been turned OFF or when operation begins or stops. They are used in the
same way as work bits.
!Caution
Never use an input bit in a NC condition on the reset (R) for KEEP(11) when
the input device uses an AC power supply (see diagram below). The delay in
shutting down the PC’s DC power supply relative to the AC power supply to
the input device can cause the designate bit of KEEP(11) to be reset.
KEEP
HR0000
B
A
AC
Set
Reset
Input Unit
A
