C24 Dsr Control - Mitsubishi Electric MELSEC iQ-R Series User Manual

Specification of free OS area
For the DTR/DSR (ER/DR) signal control, the size of the free OS area that informs data cannot be received can be set in the
parameter below.
Navigation window  [Parameter]  [Module Information]  "Module Name"  [Module Parameter]  "Basic Settings"
 "Various control specification"
Set the setting value as to be "Transmission control start free space < Transmission control end free space".
● "Transmission control start free space designation"
Specify an available capacity in the OS area in order to notify that data cannot be received (ER (DTR) signal is OFF).
• Transmission control start free space: 64 to 4,095 (Default: 64)
● "Transmission control end free space designation"
Specify an available capacity in the OS area in order to notify that data can be received (ER (DTR) signal is ON).
• Transmission control end free space: 263 to 4,096 (Default: 263)
■Remarks
• The receive data clear processing clears the data stored in the OS area. (The receive area on the buffer memory is not
cleared.) (Page 67 Receive data clear)
• If more data is received when the free area of the above mentioned OS area is 0 bytes, an SIO error occurs and the data
received until a free area is available is ignored. At that time, the SIO signal is turned ON. (Page 466 Hardware
information communication error "SIO" occurs)

C24 DSR control

C24 uses the DSR signal to detect whether or not the target device is ready to receive data and to control data transmission
to the target device as shown below, depending on whether the DSR is ON/OFF.
• If the DSR signal is ON and there is data to be transmitted, C24 transmits it to the target device.
• If the DSR signal is OFF, even if there is data to be transmitted, C24 does not transmit it to the target device.
When the DSR signal is turned ON, C24 transmits the data to the target device.
11 DATA COMMUNICATIONS USING DC CODE TRANSMISSION CONTROL
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11.1 Control Contents of DTR/DSR (ER/DR) Signal Control