Basic Specification Of Transmission Control Procedure - Hitachi EH-150 Series Applications Manual

Appendix
A.3.3

Basic specification of transmission control procedure

The communication sequence of a host and PLC is shown in the following figure.
The minimum cycle
S
T
LUMP
T
M
X
Host
PLC
In case of CPU "Busy"
S
T
LUMP
T
M
X
Host
PLC
Figure.A.5 Transmission control procedure 1 Communication sequence diagram
The minimum cycle
S
T
T
M
X
Host
PLC
In case of CPU "Busy"
S
T
T
M
X
Host
PLC
Figure.A.6 Transmission control procedure 2 Communication sequence diagram
Task S C
u
code R
m
ACK
C
Task S
u
code R
m
ACK
S C
u
Task code
R
m
S C
u
Task code R
m
ENQ
1
S Res-
C
LUMP
T ponse
R
X
ENQ ENQ
1 1
EOT EOT
S
C
T
Response
R
X
A - 10
ENQ
1
S Res-
C
LUMP
T ponse
R
X
S
C
T
Response R
X