Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 1027

Serial Communications Instructions
the Inner Board Service Disabled Flag (A42404) and the Error Flag will turn
ON.
An error will occur and the Error Flag will turn ON in the following cases.
• The CPU Unit's RS-232C port is specified, but no-protocol mode is not
set for the port in the PLC Setup.
• One of the Serial Communications Board's serial ports is specified, but
no-protocol mode is not set for the port in the allocated DM Setup Area.
• One of the Serial Communications Board's serial ports is specified, but
the Board does not support no-protocol mode (the Board does not have a
version number).
• The value of C is not within range.
• The value for N is not between 0000 and 0100 hex.
• A send was attempted when the Send Ready Flag was OFF. (The Send
Ready Flag is A39205 for the CPU Unit's RS-232C port, A35605 for Serial
Communications Board port 1, or A35613 for Serial Communications
Board port 2.)
• TXD(236) or RXD(235) was being executed for the Serial Communica-
tions Board in the cyclic task, the cyclic task was interrupted, and another
TXD(236) or RXD(235) instruction was executed for the Serial Communi-
cations Board in the interrupt task.
• TXD(236) was executed for a serial port on a Serial Communications
Board that was being restarted.
Note Do not program TXD(236)/RXD(235) for a Serial Communications Board's
port (port 1 or 2) in both the cyclic task and interrupt task. A TXD(236)/
RXD(235) instruction cannot be executed for the Serial Communications
Board in the interrupt task if a TXD(236)/RXD(235) instruction is being exe-
cuted for the Serial Communications Board in the cyclic task. An error will
occur and the ER Flag will be turned ON if a TXD(236)/RXD(235) instruction
is executed for the Serial Communications Board in the interrupt task when
another TXD(236)/RXD(235) instruction was being executed for the Serial
Communications Board in the cyclic task. (These instructions cannot be pro-
grammed in both the cyclic and interrupt tasks even if they are executed for
different ports in the Serial Communications Board.)
Section 3-24
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