Controller Link Units Operation Manual
193
Using the Message Service Section 6-3
Simultaneous Execution of Communications Instructions
C200HX/HG/HE PLCs CS/CJ-series, CVM1, and CV-series PLCs
Operating 
level #0
Operating 
level #1
Instruction 1 
Instruction 2
Instruction 3 
Instruction 4
Instruction 5 
Instruction 6
Instruction 7 
Instruction 8
Controller Link Unit
CPU Unit
Port
Controller Link Unit
CPU Unit
Port
Port
Instruction 1 
Instruction 2
There is only one communications port per operat-
ing level, so no more than one communications in-
struction can be executed per operating level at 
one time. When both operating levels are used, two 
instructions can be executed simultaneously.
There are eight communications ports, so eight 
communications can be executed simultane-
ously. Only one message is refreshed from the 
CPU Unit to the Controller Link Unit and one 
from the Controller Link Unit to the CPU Unit 
for each CPU Bus Unit service time.
CQM1H-series PLCs
There is only one communications port, so no more 
than one communications instruction can be 
executed at one time. 
Controller Link Unit
CPU Unit
Port
Instruction 1










