Panasonic FP-X0 L14R, User Manual

Page: 81 / 290

6.5 General-purpose Serial Communication
6.5.1 Overview
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In general-purpose serial communication, data is sent and received over the communication port to and
from an external device such as an image processing device or a bar code reader.
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Data is read from and written to an external device connected to the communication port by means of
PLC programs and data registers.
Outline of operation
To send data to and receive it from an external device using the general-purpose serial communication
function, the data transmission and data reception functions described below are used. The F159
(MTRN) instruction and the "reception done" flag are used in these operations, to transfer data between
the PLC and an external device.
Sending data
Data to be transmitted from the PLC is stored in
the data register used as the send buffer (DT).
When F159(MTRN) is executed, the data is output
from the communication port.
Receiving data
Data received from the communication port is
stored in the receive buffer specified in the system
register, and the "reception done" flag goes on.
Data can be received whenever the "reception
done" flag is off.
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The terminator specified in the system register is
automatically added to the data that has been
sent.
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When data is being received, the "reception
done" flag is controlled by the F159(MTRN)
instruction.
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No terminator is included in the stored data.
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