NAiS FP Series User Manual page 171

Communication Function 2 General - purpose Serial Communication
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 FPΣ and an external device.
Data transmission
Data to be output is stored in the data register used as the transmission buffer (DT), and
when the F159 (MTRN) instruction is executed, the data is output from the COM. port.
Data register (DT)
Data writing
FPΣ
Figure 163: FPΣ Data transmission
Data reception
Input data from the COM. port is stored in the received buffer specified by the system
register, and the "Reception done" flag goes on. Data can be received whenever the
"Reception done" flag is off.
Data register (DT)
Reception done
FPΣ
flag: on
Figure 164: FPΣ Data reception
9 - 4
Data transmission using
F159(MTRN) instruction
Device with
RS232C port
Data receiving
Device with
RS232C port
The end code specified by the system register is
automatically added to the data that has been
sent.
The maximum volume of data that can be sent is
2,048 bytes.
When data is received, the "Reception done" flag
is controlled by the F159 (MTRN) instruction.
No end code is included in the stored data.
The maximum volume of data that can be received
is 4,096 bytes.
FPΣ