Mitsubishi MELSEC-A series

8. MICROCOMPUTER MODE
8 − 6
MELSEC-A
POINTS
(1) The processing time of a microcomputer program called by one SUB
instruction must be 5 msec or less. If it exceeds 5 msec, operation
combination between the microcomputer program processing and the
internal processing of the PC becomes out of control and the PC cannot
run correctly.
(2) If a microcomputer program which needs more than 5 msec for processing
is to be executed, divide it into several blocks which are called
consecutively. This method can shorten the processing time of a
microcomputer program called by one SUB instruction.
8.3.1 Memory map
The microcomputer program may be used in the following areas.
8.3.2 Data memory area address configuration
One address of the data memory area consists of 16 bits which are further divided
into the odd and even areas (8 bits respectively).
Data memory area
Work area for
Microcomputer program
A1FFH
A1
0
0
H
9
FFFH
8000
H
0
8K bytes
256K bytes
For details, refer to Section 8.3.3.
Fig. 8.4 Data Memory and Work Areas
16 bits
1 address
8000H
Odd 8-bit area
(8001H)
Odd 8-bit area
(8001H)
Fig. 8.5 Configuration of 1 Address (16 bits)