104
End Codes Section 4-2
Note Occurs only for a Serial Communications Unit/Board.
A response will not be received with some errors, regardless of the command.
These errors are listed in the following table.
18 Frame length error The maximum frame length of 131
bytes was exceeded.
(If the frame exceeds 280 bytes, the
Reception Overflow Flag will be
turned ON and there will not be a
response.)
Check the command and divide it
into multiple frames if necessary.
19 Not executable The read SV exceeded 9,999, or an
I/O memory batch read was exe-
cuted when items to read were not
registered for composite command,
or access right was not obtained.
Register items to read before
attempting batch read, or obtain
access right.
20 Could not create I/O table Unrecognized Remote I/O Unit, too
many I/O words, or word duplication
used.
Check the Remote I/O System, the
number of I/O words, and the words
used.
21 Not executable due to CPU Unit
CPU error (See note.)
The command cannot be executed
because a CPU error has occurred in
the CPU Unit.
Cycle the CPU Unit’s power supply.
23 User memory protected The UM is read-protected or write-
protected.
Clear write-protection by setting pin 1
of the DIP switch on the front of the
CPU Unit to OFF. Alternatively, clear
the CPU Unit’s password-protection
using CX-Programmer.
A3 Aborted due to FCS error in trans-
mission data
An FCS error occurred in the second
or later frame, or there were two
bytes or less of data in an intermedi-
ate or final frame for multiple writing.
Correct the command data and
transfer the command again.
A4 Aborted due to format error in
transmission data
The command format did not match
the number of bytes in the second or
later frame.
A5 Aborted due to entry number data
error in transmission data
There was an entry number data
error in the second or later frame, a
data length error, or data was not set
in hexadecimal.
A8 Aborted due to frame length error in
transmission data
The length of the second and later
frames exceeded the maximum of
128 bytes.
End
code
Contents Probable cause Corrective measures
Error PLC operation
A command is received with eight bytes or less
from the @ to the delimiter.
The initial command (4 bytes) executes the initial processing. Other
commands are discarded.
Parity, overrun, or framing error during com-
mand reception. (Same even for commands
address to other Units.)
The Communications Error Flag will be turned ON, an error code will be
registered, and receptions will be reset. (The error will be cleared auto-
matically if communications restart normally.)
A command is received that does not have the
@ character at the beginning of the first frame.
The command is discarded.
Incorrect node number (Not a local unit, BCD,
or over 31)
The command is discarded.
An LF code is received after the delimiter. The LF code is discarded.
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