48
Appendix 3. Frequently Asked Questions
Communication
How do I use the operation com-
pleted flag?
The M8029 operation completed flag is shared by multiple instruc-
tions.
To obtain results indicating that the execution of a specific instruc-
tion has been completed, write the M8029 contact directly under
that instruction followed by the necessary program. You can also
use the execution completed signal after saving it using the SET
instruction.
The operation completed flag will
not turn on.
If no contact has been programmed directly under the instruction
you want to check, the flag might have been turned off by the exe-
cution of another instruction that also uses M8029.
Refer to the preceding question for details.
I am using the high-speed counter
comparison function, but the out-
put contact is not set even though
I have rewritten the current value
using the MOV instruction.
The output contact is set depending on changes to the current
value register caused by count input, so it is not set until the next
count is input, even if the value has been changed using the MOV
instruction.
When I used the comparison
(CMP) instruction, the compari-
son result still remained even
though I have turned off com-
mand input.
The comparison result is still retained even if command input has
been turned off. To clear the result, reset using the RST or ZRST
instruction.
After not using the machine that
uses FX
1N
programmable control-
ler for a while, the data register
(D7000s) value changed. What is
the cause?
Data registers D256 to D7999 of FX
1N
are capacity retainers. The
backup time is 10 days when fully charged. The value changed
because of the voltage drop in the capacitor and the data cannot
be stored correctly. If the data register and auxiliary relay are not
used as latched (battery backed) area, use the initial pulse to clear
the required scope with the ZRST instruction when the program-
mable controller is running.
To store the value for a long period of time, install an FX
1N
-BAT
type battery unit (optional) for FX
1N
.
The first special extension device
is not running in F
X3UC
.
Normally, the first special extension device number is "K0", but the
FX
3UC
-32MT-LT(-2) programmable controller has a built-in master
function for CC-Link/LT, which is set to "K0".
Set the block number for the first special extension device to "K1".
Fast (short) inputs are not read
and missed sometimes.
The ON width and OFF width for input filter time (10ms) +1 opera-
tion hour are needed for programmable controllers to load inputs
properly.
If the input is even shorter than that, use the filter adjustment func-
tion, interrupt function, pulse catch function, or the high-speed
counter.
Q
A
I want to set the communication
format.
There are two ways: Configure the communication setting using a
sequence program, or configure the "PLC parameter setting" from
a personal computer (GX Works2).
Choose one of the methods above to avoid confusion.
The communication settings are
not reflected.
After changing the communication settings, turn off and turn on the
programmable controller.
After configuring the communica-
tion setting in the RS-232C com-
munication equipment, the
personal computer (GX Works2)
and program stopped communi-
cating.
Communication settings need to be cleared (set the communica-
tion setting register value to 0) for the programmable controller and
personal computer (GX Works2) to communicate.
On GX Works2, remove the checkbox of "Communication setting"
in "PLC parameter setting (2)".
Q
A
Summary of Contents for FX Series
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