Omron CJ - REFERENCE MANUAL 02-2010 Reference Manual page 909

Hint
• Execute RXDU(255) to read the received data from the buffer when the Reception Completed Flag
(in the allocated DM Setup Area) is ON.
Precautions
• DRXDU(261) can be executed only for serial ports on a CJ1W-SCU22/SCU32/SCU42 Serial
Communications Unit. If it is executed for any other CPU Bus Unit, approximately 1 ms will be
required to execute the instruction, increasing the cycle time.
• Further data cannot be received until the received data is read from the buffer with RXDU(255) or
DRXDU(261). When the Reception Completed Flag goes ON, read that data promptly with
RXDU(255) or DRXDU(261) before more data is input to the port.
• DRXDU(261) can be used only for serial ports set to No-protocol Mode on a CJ1W-
SCU22/SCU32/SCU42 Serial Communications Unit mounted to a CJ2H CPU Unit with unit version
1.1 or later.
• 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.
• Program the Reception Completed Flag as a normally open condition of DRXDU(261) when
executing it in a cyclic task. The Reception Completed Flag cannot be used when programming
DRXDU(261) in an interrupt task. (If an external interrupt occurs, then data reception will have been
completed, so the Reception Completed Flag is not required in an interrupt task.)
• Do not restart the Serial Communications Unit during interrupt notification from the Serial
Communications Unit to the CPU Unit. Otherwise, system operation may not be stable.
CS/CJ/NSJ Series Instructions Reference Manual (W474)
3. Instructions
3
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