Omron CJ - INSTRUCTIONS REFERENCE MANUAL 07-2009 Reference Manual page 870

Precautions
• Do not enter a TXD instruction or RXD instruction for a serial port (port 1 or 2) of the serial
communication board in both a cyclic task and an interrupt task. If an interrupt task is started during
the execution of a TXD instruction or RXD instruction for a serial port (port 1 or 2) of the serial
communication board in a cyclic task, the TXD instruction or RXD instruction for a serial port (port 1
or 2) of the serial communication board cannot be executed in the interrupt task. An error will occur
and the error flag immediately after the TXD or RXD instruction in the interrupt task will turn ON. (No
combination of TXD and RXD instructions and ports 1 and 2 in a cyclic task and interrupt task is
possible.)
• RXD(235) can be used only for the CPU Unit's RS-232C port or one of the Serial Communications
Board's serial ports. In addition, the port must be set to no-protocol mode.
• Execute this instruction when the reception completion flag (RS-232C incorporated in the CPU unit:
A392.06, serial communication port 1: A356.06, or port 2: A356.14) is 1 (ON) to receive data (from
the reception buffer).
• When data is received, the data must be read by an RXD instruction or the next data cannot be
received. When the reception completion flag turns ON, read the received data with an RXD
instruction before the next reception
• Specify the size of the receive data, not including the start code and end code, in N.
• If 0 is specified for N, the Reception Completed Flag and Reception Overflow Flag will be turned OFF,
the Reception Counter will be cleared to 0, and nothing will be stored in memory.
• If the RXD(235) instruction is executed for a Board that does not support no-protocol mode (a Serial
Communications Board without a version number), the Inner Board Service Disabled Flag (A424.04,
non-fatal error) and the Error Flag will turn ON.
CS/CJ/NSJ Series Instructions Reference Manual (W474)
3. Instructions
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