Omron SYSMAC CS1W-SCB41-V1 Operation Manual page 164

Communications Timing
Host Computer Receiving Data
Response Required
Host computer
Serial Communications
Board/Unit
Communications Port Enabled Flag
No Response Required
Host computer
Serial Communications
Board/Unit
Communications Port Enabled Flag
Command transmission to the host computer can start even when the port is
receiving a command from the host computer (1). The transmission of a
response to the command from the host computer is postponed until the
transmission of the command to the host computer is completed (2).
When a response is not required from the host computer, the Communica-
tions Port Enabled Flag will turn ON when the command to the host computer
has passed from the CPU Unit to the port.
Command
Response
Command acknowledged
Command
Response
Command acknowledged
At (1) in the diagram, the response to a command sent from the host com-
puter is being transmitted from the port. In this case, the command transmis-
sion to the host computer is postponed until the response transmission is
completed (2).
When a response is not required from the host computer, the Communica-
tions Port Enabled Flag will turn ON when the command to the host computer
has passed from the CPU Unit to the port.
(1) (2)
Response
Command
(2)
(1)
Command
Command completed
Section 4-4
Command completed
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