Mitsubishi MELSEC QJ71C24, Руководство пользователя

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MELSEC-Q
3 SPECIFICATIONS
3.3.4 Enabling or disabling echo back of the RS-422/485 interface
The echo back function is enabled or disabled for CH2 of the QJ71C24N(-R4).
The echo back of the QJ71C24N(-R4) is defined as the function that, when data are
sent through RS-485 (2-wire type) from the RS-422/485 interface, the same data are
also sent to RDA or RDB of the QJ71C24N(-R4).
Whether to receive the returned data or not (discard) can be specified.
SDA
SDB
RDA
RDB
QJ71C24N(-R4)
SDA
SDB
RDA
RDB
Sending data
Target device
Receives or not receive
(discards) the data.
(1)
Application
1) Disabling the echo back will eliminate the processing for ignoring
unnecessary data, which has been programmed for non procedure protocol
communication.
2) When the same message format is used for request (command) and
response in the pre-defined protocol communication, proper communication
with the other device can be performed by disabling the echo back.
(2) Setting method
1) Setting by GX Configurator-SC
Enable or disable the function on the "CHn Transmission control and others
system setting" screen.
For details, refer to Section 9.4.5.
2) This function is set in sequence programs.
In the echo back enable/disable setting area (address: 450(1C2H)), set either
of the following values. (Default: 0)
Set value Description
0: Enable echo back
When the QJ71C24N(-R4) sends data, it also receives the sent data
in its own RDA or RDB.
1: Disable echo back
When the QJ71C24N(-R4) sends data, it does not receive the sent
data in its own RDA or RDB. (The data are discarded.)