Mitsubishi Electric melsec q03ud(E)cpu, User Manual

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CHAPTER 5 MC PROTOCOL COMMUNICATION
5
5.1 Sending a C
ommand fr
om an Ext
ernal Device to the
CPU Module
5.1.3 Pr
eca
utions
(7) Sending request messages consecutively
When request messages are sent consecutively without waiting for the reception of the response message using
4E frame, the number of commands must not exceed the limit listed as follows.
*1 If the calculation result became a decimal, the number after the decimal points will be rounded down to an integer.
Remark
If the number of commands exceeds the limit, the communication becomes in the following state. In that case, decrease
frequency of request message transmission.
• For TCP, there becomes no space in the receive buffer of the CPU module. Since the window size becomes zero,
an external device stops sending request messages until the receive buffer will have enough space.
• For UDP, an error may occur in the CPU module or the response message may not be sent from the CPU module.
TCP/UDP
Applicable number of commands for processing per one connection
*1
TCP 11680
÷
Message size (byte)
UDP
1 + (Number of messages that can be stored in receive buffer (576) ÷ Number of connections to
be used)