1018
Serial Communications Instructions Section 3-24
Related Flags and Words The following words are related to RXDU(255) operation.
DM Setup Area Settings
(m = D30000 + 100
× unit number)
Auxiliary Area
Completion Codes
Setup Area word Bit Name Settings
Port 1 Port 2
m+4 m+14 8 to 15 No-protocol Mode Start
Code
00 to FF hex
0 to 7 No-protocol Mode End
Code
00 to FF hex
m+5 m+15 12 to 15 No-protocol Mode Start
Code Specifier
0: None
1: Use start code.
8 to 11 No-protocol Mode End
Code Specifier
0: None
1: Use end code.
2: Use CR+LF.
Name Address Description
Communications
Port Enabled
Flags
A20200
to
A20207
ON when a communications instruction (including
RXDU(255)) can be executed with the corresponding
port number. Bits 00 to 07 correspond to communica-
tions ports 0 to 7.
The flag is OFF when a communications instruction is
being executed and ON when the execution is com-
pleted (normal end or error end).
Communications
Port Completion
Codes
A203 to
A210
These words contain the completion codes for the
corresponding port numbers when communications
instructions have been executed. Words A203 to
A210 correspond to communications ports 0 to 7.
The code is 00 while the instruction is being executed
and contains the relevant code when execution is
completed.
These words are cleared to 0000 when PLC opera-
tion starts.
Communications
Port Error Flags
A219 ON when an error occurred during execution of a
communications instruction. When a flag is ON,
check the completion code in A203 to A210 to trou-
bleshoot the error.
OFF when execution has been finished normally. Bits
00 to 07 correspond to communications ports 0 to 7.
The flag status is retained until the next communica-
tions instruction is executed. Even if an error has
occurred, a flag will be reset to 0 the next time that a
communications instruction is executed for that port.
Code Meaning
0205 hex Response timeout (This error can occur when the communications
mode is set to host link mode.)
0401 hex Undefined command (This error can occur when the communications
mode is set to protocol macro, NT Link, echoback test, or serial gate-
way mode.)
1001 hex The command is too long.
1002 hex The command is too short.
1004 hex The command format is incorrect.
110C hex Other parameter error
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