Mitsubishi MELSEC-A series, Programming Manual

Page: 195 / 508

6. BASIC INSTRUCTIONS
6
−
83
MELSEC-A
6.7 Link Refresh Instructions
6.7.1 Link refresh (COM)
Available Device
Bit device Word (16-bit) device Constant Pointer Level
Ca
rr
y
fla
g
Err
o
r
fla
g
X Y M L S B F T C D W R A0 A1 Z V K H P I N
D
igit specification
In
d
e
x
M9012 (M9010, M9011)
Functions (1) The COM instruction is used to make faster data communication with a remote
I/O station or to receive data positively when the scan time of the master station
sequence program is longer than that of the local station sequence program.
(2) On execution of the COM instruction, the PC CPU temporarily stops the
sequence program processing and performs general data processing (END
processing) and link refresh processing.
(3) The COM instruction may be used any number of times in the sequence
program. In this case, note that the sequence program scan time increases the
period of general data processing and link refresh times.
REMARK
By general data processing, the following processings are performed.
•
Communication between the PC and peripheral devices.
•
Monitoring of other stations.
•
Read of buffer memory of other special function modules using a computer link module.
AnS
AnN
AnSH
An A1FX
A3H
A3M
A3V AnA
AnU, A2AS
A2USH-S1
A2USH board
QCPU-A
(A Mode)
A0J2H
A2C
A52G
A73
A3N
board Applicable
CPU
O O O O X O O O
Remark * Execution is not possible while an interrupt program is being run.
COM
COM instruction executed COM instruction executed
General data processing
Link refresh
General data processing
Link refresh
* * *