User`s manual

205

CHAPTER 7 DATA COMMUNICATIONS USING DC CODE TRANSMISSION CONTROL

7.1 Control Contents of DTR/DSR (ER/DR) Signal Control

(b) Specification of free OS area

The limit of free OS area for data reception under the DTR/DSR (ER/DR) signal control is specified in GX

Configurator-SC's "Transmission control and others system setting". When it reaches the limit, this status is

notified to disable data reception.

The set values must satisfy the following condition.

"Transmission control start free area < Transmission control end free area"

• Transmission control start free area specification (Address: 2012H/2112H)

Specifies an available capacity in the OS area so that the full status is notified to disable the data reception (ER

(DTR) signal is OFF).

• Transmission control start free area: 64 to 4095 (Default: 64)

• Transmission control end free area specification (Address: 2013H/2113H)

Specifies an available capacity in the OS area so that data reception is enabled by notification (ER (DTR)

signal is ON).

• Transmission control end free area: 263 to 4096 (Default: 263)

Remark

● "Receive data clear" described in User's Manual (Basic) clears the data stored in the OS area. (The receive area in the

buffer memory is not cleared.)

● If more data is received when the OS area mentioned above are 0 byte, an SIO error is generated and the data received

until the OS area becomes vacant is ignored. At this time, the SIO signal is turned on. ( User's manual (Basic))

(2) Q series C24 DSR control

The Q series C24 uses the DSR signal to detect whether or not the external device is ready to receive data and

to control data transmission to the external device as shown below, depending on whether the DSR is on/off.

• If the DSR signal is ON and there is send data, the Q series C24 transmits it to the external device.

• If the DSR signal is OFF, even if there is send data, the Q series C24 does not transmit it to the external

device. When the DSR signal is turned on, the Q series C24 transmits the send data to the external device.