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MELSEC-Q
1 OVERVIEW
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1.1 Features
The following are features of AD51H-BASIC.
(1) Both interpreter-type BASIC and compiler-type BASIC languages
can be employed.
This allows easy creation of system control programs and programs that perform
data linking with a computer without being aware of the complicated internal
structure of the module; it is easy to use even for beginners.
The execution speed can be made faster by compiling already created programs.
(2) Multiple programs can be executed simultaneously by means of
multitask processing.
The communication module supports multitask processing. Because of this, up to
8 BASIC programs can be executed simultaneously on the AD51H-S3, and up to
2 BASIC programs can be executed simultaneously on the A1SD51S/QD51 (-
R24). In such cases, the communication module sequentially switches the
execution of each program, so it appears to the user as if the multiple programs
are running simultaneously.
(3) Data can be communicated between programs via message ports
and communication module internal devices.
When multiple programs are executed simultaneously using the multitask
processing function, data can be communicated using the following means.
1) Message ports • • • • • • • • • • • • • • • • • • • • • • •
2) Communication module internal devices • • • • •
3) Shared memory • • • • • • • • • • • • • • • • • • • • • • •
1 to n data communication
1 to n data communication
1 to n data communication
(4) Execution can be synchronized between programs via events.
When multiple programs are executed simultaneously using the multitask
processing function, it is possible to synchronize their executions. This is
achieved by making programs wait for an event using the ZWAIT EVENT
instruction and generating an event by the ZSIGNAL instruction.
(5) Instructions for data link with external devices have been unified.
Data link with the PLC CPU of the same station as the communication module or
other PLC CPUs via MELSECNET can be performed using the PCRD/PCWT
instructions. The data link between the various interfaces of the communication
module and external devices is performed using the ZRECEIVE/ZSEND
instructions.
In this way, by creating a single subroutine that performs data link, it is possible
to share the arguments of each instruction by passing them to variables in that
subroutine.
