User`s manual

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6.4 Message Wait Time Setting
The message wait time is used during data communications using a MC protocol.
It is the time for an external device that cannot receive the data immediately after it has been transmitted.
When the Q series C24 transmits a response message in reply to a command message received from the external
device, transmission of the response message is delayed by the message wait time, or longer.
The following explains the message wait time operation for data communications using QnA compatible 2C/3C/4C
frame. (For A compatible 1C frames, the message wait time is designated in the command message.)
(1) Q series C24 operation by message wait time
• When message wait time is 0ms
If a response message can be transmitted, the Q series C24 immediately transmits the response message. A
transmission wait time is not set.
• When the message wait time is 10ms or longer
If a response message can be transmitted, and the message wait time after reception of the command message
has elapsed, the Q series C24 transmits the response message.
(2) Changing the transmission wait time
The transmission wait time is registered on the GX Configurator-SC's "MC protocol system setting" screen
● If the external device that must wait a certain time before it can receive a response message after a command message
was transmitted, set the message wait time as explained above. Especially, for data communications with an external
device connected to the Q series C24 RS-422/485 interface, set the message wait time to the external device hardware
gate OFF time or longer.
● The message wait time described here is the time for data communications using QnA compatible 2C/3C/4C frame.
Response message
Command message
Message wait time
External
device
Programmable
controller CPU