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Precautions during programming (in the case of SCU)
● Use the UNITSEL instruction immediately before the GPRECV instruction to specify a target
port for communication.
● When the general-purpose communication received flag is ON for the targeted COM port,
execute GPRECV.
● When multiplex reception is in progress, the received flag remains ON after the received
data have been copied using the GPRECV instruction. The received data cannot be copied
at the leading edge of the reception done signal.
● The received data copied by the GPRECV instruction do not include a start code or an end
code.
● It is also possible to receive binary data using the GPRECV instruction. In this case, "time"
should be used for the end setting.
● The received data or the received data amount do not include the end code. (It is stripped
off.)
● In the case of SCU which has eight 4096-byte buffers inside, data equivalent to the eight
buffers can be received consecutively.
● If the reception of the ninth datum of data is performed by SCU before the GPRECV
instruction is executed to take out data from SCU's receive buffer, a buffer FULL error occurs
in SCU, and the ninth datum is discarded.
● If the GPRECV instruction is executed when the receive buffer FULL error is on, the oldest
received datum is taken out, and the receive buffer FULL error is canceled.
● When no data have been received, the general-purpose communication control flag
(received copy flag) turns OFF.
● After data have been received, and copy to the operation memory of the CPU unit has been
completed, the general-purpose communication control flag (received data copied flag) turns
ON.
● In the case of a direct address and an index modification address, specify the same device
for D1 and D2. At the same time, specify the addresses so that D1 is less than D2.
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Sample program (in the case of CPU with built-in ET-LAN)
● When the received flag (X70) of Connection 1 turns ON, the reception program is started up
by the GPRECV instruction.
● The UNITSEL instruction is used to specify a slot number (LAN port: U100) and the
connection number (U1).
● In the GPRECV instruction, specify and execute the start of the data table that stores the
received message (DT200) and the final address (DT209).
GPRECV ．US
DT209DT200
R100
UNITSEL U1U100
GPRECV instruction execution
D1: Header for received data (DT200)
D2 : End for received data (DT209)
GPRECV execution condition
Received flag: ON
S1 S2
D1 D2
Communication port settings
S1: CPU LAN port (U100)
S2: Connection 1 (U1)
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Time chart (in the case of CPU with built-in ET-LAN)
● Data received from an external device are stored in the receive buffer for each connection.
9.4 Receiving Operation
WUME-FP7COM-07 9-25
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