Omron SYSMAC C200H-ASC02, Руководство по эксплуатации

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16
3-1 Programs
To use the ASCII Unit in conjunction with the PC, an ASCII Unit program writ-
ten in BASIC is needed. A data exchange routine must also be incorporated
into the PC program except when the READ(@...) and WRITE(@...) state-
ments are used with specific memory area designators. The PC data ex-
change routine must set the number of words to be transferred, the base
address, and the specific memory area. This can be done using the PC MOV
instruction.
There are two ways the ASCII Unit can communicate with the PC. In the first
method, the PC controls the timing of the data transfer between the two de-
vices. The ASCII Unit “requests” access to the PC data memory area using
the PC READ, PC WRITE, PC GET, or PC PUT statements, and then waits
for the PC to respond by setting either the read or write flag. The PC data
exchange routine performs the designated operations. When the PC is ready,
the appropriate flag is set and the ASCII Unit proceeds with the data transfer.
In the second method, no special PC data exchange code is necessary to
facilitate communication between the two devices. If the memory area desig-
nator parameter is specified with the PC READ or PC WRITE statement, the
ASCII Unit can directly access the specified PC memory area.
The following two figures illustrate the relationship between the PC program
and the ASCII Unit program.
PC program
General Program
General Program
Data exchange
code
ASCII Unit program
Data exchange
processing or I/
O program
write/read
data
exchange
PC program
I/O data ex-
change
ASCII Unit program
Common
memory
I/O
memory
This diagram illustrates the relationship between the PC data exchange code
and the ASCII Unit program.
PC READ command
PC WRITE command
PC PUT command
PC GET command
MOV Instruction
MOV instruction, OUT
instruction, etc.
MOV Instruction
MOV instruction, OUT
instruction, etc.
I/O
memory
Programs
Section 3-1